3949 lines
98 KiB
C
3949 lines
98 KiB
C
/*
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* CFQ, or complete fairness queueing, disk scheduler.
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*
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* Based on ideas from a previously unfinished io
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* scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
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*
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* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/blkdev.h>
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#include <linux/elevator.h>
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#include <linux/jiffies.h>
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#include <linux/rbtree.h>
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#include <linux/ioprio.h>
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#include <linux/blktrace_api.h>
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#include "blk-cgroup.h"
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/*
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* tunables
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*/
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/* max queue in one round of service */
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static const int cfq_quantum = 8;
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static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
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/* maximum backwards seek, in KiB */
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static const int cfq_back_max = 16 * 1024;
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/* penalty of a backwards seek */
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static const int cfq_back_penalty = 2;
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static const int cfq_slice_sync = HZ / 10;
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static int cfq_slice_async = HZ / 25;
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static const int cfq_slice_async_rq = 2;
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static int cfq_slice_idle = HZ / 125;
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static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
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static const int cfq_hist_divisor = 4;
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/*
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* offset from end of service tree
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*/
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#define CFQ_IDLE_DELAY (HZ / 5)
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/*
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* below this threshold, we consider thinktime immediate
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*/
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#define CFQ_MIN_TT (2)
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#define CFQ_SLICE_SCALE (5)
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#define CFQ_HW_QUEUE_MIN (5)
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#define CFQ_SERVICE_SHIFT 12
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#define CFQQ_SEEK_THR (sector_t)(8 * 100)
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#define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
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#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
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#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
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#define RQ_CIC(rq) \
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((struct cfq_io_context *) (rq)->elevator_private)
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#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
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static struct kmem_cache *cfq_pool;
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static struct kmem_cache *cfq_ioc_pool;
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static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
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static struct completion *ioc_gone;
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static DEFINE_SPINLOCK(ioc_gone_lock);
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#define CFQ_PRIO_LISTS IOPRIO_BE_NR
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#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
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#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
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#define sample_valid(samples) ((samples) > 80)
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#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
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/*
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* Most of our rbtree usage is for sorting with min extraction, so
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* if we cache the leftmost node we don't have to walk down the tree
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* to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
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* move this into the elevator for the rq sorting as well.
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*/
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struct cfq_rb_root {
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struct rb_root rb;
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struct rb_node *left;
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unsigned count;
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unsigned total_weight;
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u64 min_vdisktime;
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struct rb_node *active;
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};
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#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
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.count = 0, .min_vdisktime = 0, }
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/*
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* Per process-grouping structure
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*/
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struct cfq_queue {
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/* reference count */
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atomic_t ref;
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/* various state flags, see below */
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unsigned int flags;
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/* parent cfq_data */
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struct cfq_data *cfqd;
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/* service_tree member */
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struct rb_node rb_node;
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/* service_tree key */
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unsigned long rb_key;
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/* prio tree member */
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struct rb_node p_node;
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/* prio tree root we belong to, if any */
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struct rb_root *p_root;
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/* sorted list of pending requests */
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struct rb_root sort_list;
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/* if fifo isn't expired, next request to serve */
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struct request *next_rq;
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/* requests queued in sort_list */
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int queued[2];
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/* currently allocated requests */
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int allocated[2];
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/* fifo list of requests in sort_list */
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struct list_head fifo;
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/* time when queue got scheduled in to dispatch first request. */
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unsigned long dispatch_start;
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unsigned int allocated_slice;
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unsigned int slice_dispatch;
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/* time when first request from queue completed and slice started. */
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unsigned long slice_start;
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unsigned long slice_end;
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long slice_resid;
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/* pending metadata requests */
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int meta_pending;
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/* number of requests that are on the dispatch list or inside driver */
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int dispatched;
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/* io prio of this group */
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unsigned short ioprio, org_ioprio;
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unsigned short ioprio_class, org_ioprio_class;
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pid_t pid;
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u32 seek_history;
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sector_t last_request_pos;
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struct cfq_rb_root *service_tree;
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struct cfq_queue *new_cfqq;
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struct cfq_group *cfqg;
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struct cfq_group *orig_cfqg;
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/* Sectors dispatched in current dispatch round */
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unsigned long nr_sectors;
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};
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/*
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* First index in the service_trees.
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* IDLE is handled separately, so it has negative index
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*/
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enum wl_prio_t {
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BE_WORKLOAD = 0,
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RT_WORKLOAD = 1,
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IDLE_WORKLOAD = 2,
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};
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/*
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* Second index in the service_trees.
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*/
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enum wl_type_t {
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ASYNC_WORKLOAD = 0,
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SYNC_NOIDLE_WORKLOAD = 1,
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SYNC_WORKLOAD = 2
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};
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/* This is per cgroup per device grouping structure */
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struct cfq_group {
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/* group service_tree member */
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struct rb_node rb_node;
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/* group service_tree key */
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u64 vdisktime;
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unsigned int weight;
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bool on_st;
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/* number of cfqq currently on this group */
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int nr_cfqq;
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/* Per group busy queus average. Useful for workload slice calc. */
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unsigned int busy_queues_avg[2];
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/*
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* rr lists of queues with requests, onle rr for each priority class.
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* Counts are embedded in the cfq_rb_root
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*/
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struct cfq_rb_root service_trees[2][3];
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struct cfq_rb_root service_tree_idle;
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unsigned long saved_workload_slice;
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enum wl_type_t saved_workload;
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enum wl_prio_t saved_serving_prio;
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struct blkio_group blkg;
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#ifdef CONFIG_CFQ_GROUP_IOSCHED
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struct hlist_node cfqd_node;
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atomic_t ref;
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#endif
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};
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/*
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* Per block device queue structure
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*/
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struct cfq_data {
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struct request_queue *queue;
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/* Root service tree for cfq_groups */
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struct cfq_rb_root grp_service_tree;
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struct cfq_group root_group;
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/*
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* The priority currently being served
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*/
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enum wl_prio_t serving_prio;
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enum wl_type_t serving_type;
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unsigned long workload_expires;
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struct cfq_group *serving_group;
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bool noidle_tree_requires_idle;
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/*
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* Each priority tree is sorted by next_request position. These
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* trees are used when determining if two or more queues are
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* interleaving requests (see cfq_close_cooperator).
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*/
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struct rb_root prio_trees[CFQ_PRIO_LISTS];
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unsigned int busy_queues;
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int rq_in_driver;
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int rq_in_flight[2];
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/*
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* queue-depth detection
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*/
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int rq_queued;
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int hw_tag;
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/*
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* hw_tag can be
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* -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
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* 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
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* 0 => no NCQ
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*/
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int hw_tag_est_depth;
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unsigned int hw_tag_samples;
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/*
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* idle window management
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*/
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struct timer_list idle_slice_timer;
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struct work_struct unplug_work;
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struct cfq_queue *active_queue;
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struct cfq_io_context *active_cic;
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/*
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* async queue for each priority case
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*/
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struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
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struct cfq_queue *async_idle_cfqq;
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sector_t last_position;
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/*
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* tunables, see top of file
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*/
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unsigned int cfq_quantum;
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unsigned int cfq_fifo_expire[2];
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unsigned int cfq_back_penalty;
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unsigned int cfq_back_max;
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unsigned int cfq_slice[2];
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unsigned int cfq_slice_async_rq;
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unsigned int cfq_slice_idle;
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unsigned int cfq_latency;
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unsigned int cfq_group_isolation;
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struct list_head cic_list;
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/*
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* Fallback dummy cfqq for extreme OOM conditions
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*/
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struct cfq_queue oom_cfqq;
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unsigned long last_delayed_sync;
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/* List of cfq groups being managed on this device*/
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struct hlist_head cfqg_list;
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struct rcu_head rcu;
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};
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static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
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static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
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enum wl_prio_t prio,
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enum wl_type_t type)
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{
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if (!cfqg)
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return NULL;
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if (prio == IDLE_WORKLOAD)
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return &cfqg->service_tree_idle;
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return &cfqg->service_trees[prio][type];
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}
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enum cfqq_state_flags {
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CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
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CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
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CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
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CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
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CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
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CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
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CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
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CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
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CFQ_CFQQ_FLAG_sync, /* synchronous queue */
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CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
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CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
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CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
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CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
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};
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#define CFQ_CFQQ_FNS(name) \
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static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
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{ \
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(cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
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} \
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static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
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{ \
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(cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
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} \
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static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
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{ \
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return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
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}
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CFQ_CFQQ_FNS(on_rr);
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CFQ_CFQQ_FNS(wait_request);
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CFQ_CFQQ_FNS(must_dispatch);
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CFQ_CFQQ_FNS(must_alloc_slice);
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CFQ_CFQQ_FNS(fifo_expire);
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CFQ_CFQQ_FNS(idle_window);
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CFQ_CFQQ_FNS(prio_changed);
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CFQ_CFQQ_FNS(slice_new);
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CFQ_CFQQ_FNS(sync);
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CFQ_CFQQ_FNS(coop);
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CFQ_CFQQ_FNS(split_coop);
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CFQ_CFQQ_FNS(deep);
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CFQ_CFQQ_FNS(wait_busy);
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#undef CFQ_CFQQ_FNS
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#ifdef CONFIG_DEBUG_CFQ_IOSCHED
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#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
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blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
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cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
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blkg_path(&(cfqq)->cfqg->blkg), ##args);
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#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
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blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
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blkg_path(&(cfqg)->blkg), ##args); \
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#else
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#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
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blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
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#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
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#endif
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#define cfq_log(cfqd, fmt, args...) \
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blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
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/* Traverses through cfq group service trees */
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#define for_each_cfqg_st(cfqg, i, j, st) \
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for (i = 0; i <= IDLE_WORKLOAD; i++) \
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for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
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: &cfqg->service_tree_idle; \
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(i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
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(i == IDLE_WORKLOAD && j == 0); \
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j++, st = i < IDLE_WORKLOAD ? \
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&cfqg->service_trees[i][j]: NULL) \
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static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
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{
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if (cfq_class_idle(cfqq))
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return IDLE_WORKLOAD;
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if (cfq_class_rt(cfqq))
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return RT_WORKLOAD;
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return BE_WORKLOAD;
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}
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static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
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{
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if (!cfq_cfqq_sync(cfqq))
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return ASYNC_WORKLOAD;
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if (!cfq_cfqq_idle_window(cfqq))
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return SYNC_NOIDLE_WORKLOAD;
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return SYNC_WORKLOAD;
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}
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static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
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struct cfq_data *cfqd,
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struct cfq_group *cfqg)
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{
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if (wl == IDLE_WORKLOAD)
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return cfqg->service_tree_idle.count;
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return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
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+ cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
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+ cfqg->service_trees[wl][SYNC_WORKLOAD].count;
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}
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static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
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struct cfq_group *cfqg)
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{
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return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
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+ cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
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}
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static void cfq_dispatch_insert(struct request_queue *, struct request *);
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static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
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struct io_context *, gfp_t);
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static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
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struct io_context *);
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static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
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bool is_sync)
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{
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return cic->cfqq[is_sync];
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}
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static inline void cic_set_cfqq(struct cfq_io_context *cic,
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struct cfq_queue *cfqq, bool is_sync)
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{
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cic->cfqq[is_sync] = cfqq;
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}
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/*
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* We regard a request as SYNC, if it's either a read or has the SYNC bit
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* set (in which case it could also be direct WRITE).
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*/
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static inline bool cfq_bio_sync(struct bio *bio)
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{
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return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO);
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}
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/*
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* scheduler run of queue, if there are requests pending and no one in the
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* driver that will restart queueing
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*/
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static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
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{
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if (cfqd->busy_queues) {
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cfq_log(cfqd, "schedule dispatch");
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kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
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}
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}
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static int cfq_queue_empty(struct request_queue *q)
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{
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struct cfq_data *cfqd = q->elevator->elevator_data;
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return !cfqd->rq_queued;
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}
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/*
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* Scale schedule slice based on io priority. Use the sync time slice only
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* if a queue is marked sync and has sync io queued. A sync queue with async
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* io only, should not get full sync slice length.
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*/
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static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
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unsigned short prio)
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{
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const int base_slice = cfqd->cfq_slice[sync];
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WARN_ON(prio >= IOPRIO_BE_NR);
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return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
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}
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static inline int
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cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
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{
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return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
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}
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static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
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{
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u64 d = delta << CFQ_SERVICE_SHIFT;
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|
|
|
d = d * BLKIO_WEIGHT_DEFAULT;
|
|
do_div(d, cfqg->weight);
|
|
return d;
|
|
}
|
|
|
|
static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
|
|
{
|
|
s64 delta = (s64)(vdisktime - min_vdisktime);
|
|
if (delta > 0)
|
|
min_vdisktime = vdisktime;
|
|
|
|
return min_vdisktime;
|
|
}
|
|
|
|
static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
|
|
{
|
|
s64 delta = (s64)(vdisktime - min_vdisktime);
|
|
if (delta < 0)
|
|
min_vdisktime = vdisktime;
|
|
|
|
return min_vdisktime;
|
|
}
|
|
|
|
static void update_min_vdisktime(struct cfq_rb_root *st)
|
|
{
|
|
u64 vdisktime = st->min_vdisktime;
|
|
struct cfq_group *cfqg;
|
|
|
|
if (st->active) {
|
|
cfqg = rb_entry_cfqg(st->active);
|
|
vdisktime = cfqg->vdisktime;
|
|
}
|
|
|
|
if (st->left) {
|
|
cfqg = rb_entry_cfqg(st->left);
|
|
vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
|
|
}
|
|
|
|
st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
|
|
}
|
|
|
|
/*
|
|
* get averaged number of queues of RT/BE priority.
|
|
* average is updated, with a formula that gives more weight to higher numbers,
|
|
* to quickly follows sudden increases and decrease slowly
|
|
*/
|
|
|
|
static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
|
|
struct cfq_group *cfqg, bool rt)
|
|
{
|
|
unsigned min_q, max_q;
|
|
unsigned mult = cfq_hist_divisor - 1;
|
|
unsigned round = cfq_hist_divisor / 2;
|
|
unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
|
|
|
|
min_q = min(cfqg->busy_queues_avg[rt], busy);
|
|
max_q = max(cfqg->busy_queues_avg[rt], busy);
|
|
cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
|
|
cfq_hist_divisor;
|
|
return cfqg->busy_queues_avg[rt];
|
|
}
|
|
|
|
static inline unsigned
|
|
cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
|
|
{
|
|
struct cfq_rb_root *st = &cfqd->grp_service_tree;
|
|
|
|
return cfq_target_latency * cfqg->weight / st->total_weight;
|
|
}
|
|
|
|
static inline void
|
|
cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
|
|
if (cfqd->cfq_latency) {
|
|
/*
|
|
* interested queues (we consider only the ones with the same
|
|
* priority class in the cfq group)
|
|
*/
|
|
unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
|
|
cfq_class_rt(cfqq));
|
|
unsigned sync_slice = cfqd->cfq_slice[1];
|
|
unsigned expect_latency = sync_slice * iq;
|
|
unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
|
|
|
|
if (expect_latency > group_slice) {
|
|
unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
|
|
/* scale low_slice according to IO priority
|
|
* and sync vs async */
|
|
unsigned low_slice =
|
|
min(slice, base_low_slice * slice / sync_slice);
|
|
/* the adapted slice value is scaled to fit all iqs
|
|
* into the target latency */
|
|
slice = max(slice * group_slice / expect_latency,
|
|
low_slice);
|
|
}
|
|
}
|
|
cfqq->slice_start = jiffies;
|
|
cfqq->slice_end = jiffies + slice;
|
|
cfqq->allocated_slice = slice;
|
|
cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
|
|
}
|
|
|
|
/*
|
|
* We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
|
|
* isn't valid until the first request from the dispatch is activated
|
|
* and the slice time set.
|
|
*/
|
|
static inline bool cfq_slice_used(struct cfq_queue *cfqq)
|
|
{
|
|
if (cfq_cfqq_slice_new(cfqq))
|
|
return 0;
|
|
if (time_before(jiffies, cfqq->slice_end))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Lifted from AS - choose which of rq1 and rq2 that is best served now.
|
|
* We choose the request that is closest to the head right now. Distance
|
|
* behind the head is penalized and only allowed to a certain extent.
|
|
*/
|
|
static struct request *
|
|
cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
|
|
{
|
|
sector_t s1, s2, d1 = 0, d2 = 0;
|
|
unsigned long back_max;
|
|
#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
|
|
#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
|
|
unsigned wrap = 0; /* bit mask: requests behind the disk head? */
|
|
|
|
if (rq1 == NULL || rq1 == rq2)
|
|
return rq2;
|
|
if (rq2 == NULL)
|
|
return rq1;
|
|
|
|
if (rq_is_sync(rq1) && !rq_is_sync(rq2))
|
|
return rq1;
|
|
else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
|
|
return rq2;
|
|
if (rq_is_meta(rq1) && !rq_is_meta(rq2))
|
|
return rq1;
|
|
else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
|
|
return rq2;
|
|
|
|
s1 = blk_rq_pos(rq1);
|
|
s2 = blk_rq_pos(rq2);
|
|
|
|
/*
|
|
* by definition, 1KiB is 2 sectors
|
|
*/
|
|
back_max = cfqd->cfq_back_max * 2;
|
|
|
|
/*
|
|
* Strict one way elevator _except_ in the case where we allow
|
|
* short backward seeks which are biased as twice the cost of a
|
|
* similar forward seek.
|
|
*/
|
|
if (s1 >= last)
|
|
d1 = s1 - last;
|
|
else if (s1 + back_max >= last)
|
|
d1 = (last - s1) * cfqd->cfq_back_penalty;
|
|
else
|
|
wrap |= CFQ_RQ1_WRAP;
|
|
|
|
if (s2 >= last)
|
|
d2 = s2 - last;
|
|
else if (s2 + back_max >= last)
|
|
d2 = (last - s2) * cfqd->cfq_back_penalty;
|
|
else
|
|
wrap |= CFQ_RQ2_WRAP;
|
|
|
|
/* Found required data */
|
|
|
|
/*
|
|
* By doing switch() on the bit mask "wrap" we avoid having to
|
|
* check two variables for all permutations: --> faster!
|
|
*/
|
|
switch (wrap) {
|
|
case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
|
|
if (d1 < d2)
|
|
return rq1;
|
|
else if (d2 < d1)
|
|
return rq2;
|
|
else {
|
|
if (s1 >= s2)
|
|
return rq1;
|
|
else
|
|
return rq2;
|
|
}
|
|
|
|
case CFQ_RQ2_WRAP:
|
|
return rq1;
|
|
case CFQ_RQ1_WRAP:
|
|
return rq2;
|
|
case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
|
|
default:
|
|
/*
|
|
* Since both rqs are wrapped,
|
|
* start with the one that's further behind head
|
|
* (--> only *one* back seek required),
|
|
* since back seek takes more time than forward.
|
|
*/
|
|
if (s1 <= s2)
|
|
return rq1;
|
|
else
|
|
return rq2;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The below is leftmost cache rbtree addon
|
|
*/
|
|
static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
|
|
{
|
|
/* Service tree is empty */
|
|
if (!root->count)
|
|
return NULL;
|
|
|
|
if (!root->left)
|
|
root->left = rb_first(&root->rb);
|
|
|
|
if (root->left)
|
|
return rb_entry(root->left, struct cfq_queue, rb_node);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
|
|
{
|
|
if (!root->left)
|
|
root->left = rb_first(&root->rb);
|
|
|
|
if (root->left)
|
|
return rb_entry_cfqg(root->left);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void rb_erase_init(struct rb_node *n, struct rb_root *root)
|
|
{
|
|
rb_erase(n, root);
|
|
RB_CLEAR_NODE(n);
|
|
}
|
|
|
|
static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
|
|
{
|
|
if (root->left == n)
|
|
root->left = NULL;
|
|
rb_erase_init(n, &root->rb);
|
|
--root->count;
|
|
}
|
|
|
|
/*
|
|
* would be nice to take fifo expire time into account as well
|
|
*/
|
|
static struct request *
|
|
cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct request *last)
|
|
{
|
|
struct rb_node *rbnext = rb_next(&last->rb_node);
|
|
struct rb_node *rbprev = rb_prev(&last->rb_node);
|
|
struct request *next = NULL, *prev = NULL;
|
|
|
|
BUG_ON(RB_EMPTY_NODE(&last->rb_node));
|
|
|
|
if (rbprev)
|
|
prev = rb_entry_rq(rbprev);
|
|
|
|
if (rbnext)
|
|
next = rb_entry_rq(rbnext);
|
|
else {
|
|
rbnext = rb_first(&cfqq->sort_list);
|
|
if (rbnext && rbnext != &last->rb_node)
|
|
next = rb_entry_rq(rbnext);
|
|
}
|
|
|
|
return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
|
|
}
|
|
|
|
static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
/*
|
|
* just an approximation, should be ok.
|
|
*/
|
|
return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
|
|
cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
|
|
}
|
|
|
|
static inline s64
|
|
cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
|
|
{
|
|
return cfqg->vdisktime - st->min_vdisktime;
|
|
}
|
|
|
|
static void
|
|
__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
|
|
{
|
|
struct rb_node **node = &st->rb.rb_node;
|
|
struct rb_node *parent = NULL;
|
|
struct cfq_group *__cfqg;
|
|
s64 key = cfqg_key(st, cfqg);
|
|
int left = 1;
|
|
|
|
while (*node != NULL) {
|
|
parent = *node;
|
|
__cfqg = rb_entry_cfqg(parent);
|
|
|
|
if (key < cfqg_key(st, __cfqg))
|
|
node = &parent->rb_left;
|
|
else {
|
|
node = &parent->rb_right;
|
|
left = 0;
|
|
}
|
|
}
|
|
|
|
if (left)
|
|
st->left = &cfqg->rb_node;
|
|
|
|
rb_link_node(&cfqg->rb_node, parent, node);
|
|
rb_insert_color(&cfqg->rb_node, &st->rb);
|
|
}
|
|
|
|
static void
|
|
cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
|
|
{
|
|
struct cfq_rb_root *st = &cfqd->grp_service_tree;
|
|
struct cfq_group *__cfqg;
|
|
struct rb_node *n;
|
|
|
|
cfqg->nr_cfqq++;
|
|
if (cfqg->on_st)
|
|
return;
|
|
|
|
/*
|
|
* Currently put the group at the end. Later implement something
|
|
* so that groups get lesser vtime based on their weights, so that
|
|
* if group does not loose all if it was not continously backlogged.
|
|
*/
|
|
n = rb_last(&st->rb);
|
|
if (n) {
|
|
__cfqg = rb_entry_cfqg(n);
|
|
cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
|
|
} else
|
|
cfqg->vdisktime = st->min_vdisktime;
|
|
|
|
__cfq_group_service_tree_add(st, cfqg);
|
|
cfqg->on_st = true;
|
|
st->total_weight += cfqg->weight;
|
|
}
|
|
|
|
static void
|
|
cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
|
|
{
|
|
struct cfq_rb_root *st = &cfqd->grp_service_tree;
|
|
|
|
if (st->active == &cfqg->rb_node)
|
|
st->active = NULL;
|
|
|
|
BUG_ON(cfqg->nr_cfqq < 1);
|
|
cfqg->nr_cfqq--;
|
|
|
|
/* If there are other cfq queues under this group, don't delete it */
|
|
if (cfqg->nr_cfqq)
|
|
return;
|
|
|
|
cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
|
|
cfqg->on_st = false;
|
|
st->total_weight -= cfqg->weight;
|
|
if (!RB_EMPTY_NODE(&cfqg->rb_node))
|
|
cfq_rb_erase(&cfqg->rb_node, st);
|
|
cfqg->saved_workload_slice = 0;
|
|
blkiocg_update_blkio_group_dequeue_stats(&cfqg->blkg, 1);
|
|
}
|
|
|
|
static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
|
|
{
|
|
unsigned int slice_used;
|
|
|
|
/*
|
|
* Queue got expired before even a single request completed or
|
|
* got expired immediately after first request completion.
|
|
*/
|
|
if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
|
|
/*
|
|
* Also charge the seek time incurred to the group, otherwise
|
|
* if there are mutiple queues in the group, each can dispatch
|
|
* a single request on seeky media and cause lots of seek time
|
|
* and group will never know it.
|
|
*/
|
|
slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
|
|
1);
|
|
} else {
|
|
slice_used = jiffies - cfqq->slice_start;
|
|
if (slice_used > cfqq->allocated_slice)
|
|
slice_used = cfqq->allocated_slice;
|
|
}
|
|
|
|
cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u sect=%lu", slice_used,
|
|
cfqq->nr_sectors);
|
|
return slice_used;
|
|
}
|
|
|
|
static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_rb_root *st = &cfqd->grp_service_tree;
|
|
unsigned int used_sl, charge_sl;
|
|
int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
|
|
- cfqg->service_tree_idle.count;
|
|
|
|
BUG_ON(nr_sync < 0);
|
|
used_sl = charge_sl = cfq_cfqq_slice_usage(cfqq);
|
|
|
|
if (!cfq_cfqq_sync(cfqq) && !nr_sync)
|
|
charge_sl = cfqq->allocated_slice;
|
|
|
|
/* Can't update vdisktime while group is on service tree */
|
|
cfq_rb_erase(&cfqg->rb_node, st);
|
|
cfqg->vdisktime += cfq_scale_slice(charge_sl, cfqg);
|
|
__cfq_group_service_tree_add(st, cfqg);
|
|
|
|
/* This group is being expired. Save the context */
|
|
if (time_after(cfqd->workload_expires, jiffies)) {
|
|
cfqg->saved_workload_slice = cfqd->workload_expires
|
|
- jiffies;
|
|
cfqg->saved_workload = cfqd->serving_type;
|
|
cfqg->saved_serving_prio = cfqd->serving_prio;
|
|
} else
|
|
cfqg->saved_workload_slice = 0;
|
|
|
|
cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
|
|
st->min_vdisktime);
|
|
blkiocg_update_blkio_group_stats(&cfqg->blkg, used_sl,
|
|
cfqq->nr_sectors);
|
|
}
|
|
|
|
#ifdef CONFIG_CFQ_GROUP_IOSCHED
|
|
static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
|
|
{
|
|
if (blkg)
|
|
return container_of(blkg, struct cfq_group, blkg);
|
|
return NULL;
|
|
}
|
|
|
|
void
|
|
cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight)
|
|
{
|
|
cfqg_of_blkg(blkg)->weight = weight;
|
|
}
|
|
|
|
static struct cfq_group *
|
|
cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
|
|
{
|
|
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
|
|
struct cfq_group *cfqg = NULL;
|
|
void *key = cfqd;
|
|
int i, j;
|
|
struct cfq_rb_root *st;
|
|
struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
|
|
unsigned int major, minor;
|
|
|
|
cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
|
|
if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
|
|
sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
|
|
cfqg->blkg.dev = MKDEV(major, minor);
|
|
goto done;
|
|
}
|
|
if (cfqg || !create)
|
|
goto done;
|
|
|
|
cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
|
|
if (!cfqg)
|
|
goto done;
|
|
|
|
cfqg->weight = blkcg->weight;
|
|
for_each_cfqg_st(cfqg, i, j, st)
|
|
*st = CFQ_RB_ROOT;
|
|
RB_CLEAR_NODE(&cfqg->rb_node);
|
|
|
|
/*
|
|
* Take the initial reference that will be released on destroy
|
|
* This can be thought of a joint reference by cgroup and
|
|
* elevator which will be dropped by either elevator exit
|
|
* or cgroup deletion path depending on who is exiting first.
|
|
*/
|
|
atomic_set(&cfqg->ref, 1);
|
|
|
|
/* Add group onto cgroup list */
|
|
sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
|
|
blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
|
|
MKDEV(major, minor));
|
|
|
|
/* Add group on cfqd list */
|
|
hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
|
|
|
|
done:
|
|
return cfqg;
|
|
}
|
|
|
|
/*
|
|
* Search for the cfq group current task belongs to. If create = 1, then also
|
|
* create the cfq group if it does not exist. request_queue lock must be held.
|
|
*/
|
|
static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
|
|
{
|
|
struct cgroup *cgroup;
|
|
struct cfq_group *cfqg = NULL;
|
|
|
|
rcu_read_lock();
|
|
cgroup = task_cgroup(current, blkio_subsys_id);
|
|
cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
|
|
if (!cfqg && create)
|
|
cfqg = &cfqd->root_group;
|
|
rcu_read_unlock();
|
|
return cfqg;
|
|
}
|
|
|
|
static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
|
|
{
|
|
/* Currently, all async queues are mapped to root group */
|
|
if (!cfq_cfqq_sync(cfqq))
|
|
cfqg = &cfqq->cfqd->root_group;
|
|
|
|
cfqq->cfqg = cfqg;
|
|
/* cfqq reference on cfqg */
|
|
atomic_inc(&cfqq->cfqg->ref);
|
|
}
|
|
|
|
static void cfq_put_cfqg(struct cfq_group *cfqg)
|
|
{
|
|
struct cfq_rb_root *st;
|
|
int i, j;
|
|
|
|
BUG_ON(atomic_read(&cfqg->ref) <= 0);
|
|
if (!atomic_dec_and_test(&cfqg->ref))
|
|
return;
|
|
for_each_cfqg_st(cfqg, i, j, st)
|
|
BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
|
|
kfree(cfqg);
|
|
}
|
|
|
|
static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
|
|
{
|
|
/* Something wrong if we are trying to remove same group twice */
|
|
BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
|
|
|
|
hlist_del_init(&cfqg->cfqd_node);
|
|
|
|
/*
|
|
* Put the reference taken at the time of creation so that when all
|
|
* queues are gone, group can be destroyed.
|
|
*/
|
|
cfq_put_cfqg(cfqg);
|
|
}
|
|
|
|
static void cfq_release_cfq_groups(struct cfq_data *cfqd)
|
|
{
|
|
struct hlist_node *pos, *n;
|
|
struct cfq_group *cfqg;
|
|
|
|
hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
|
|
/*
|
|
* If cgroup removal path got to blk_group first and removed
|
|
* it from cgroup list, then it will take care of destroying
|
|
* cfqg also.
|
|
*/
|
|
if (!blkiocg_del_blkio_group(&cfqg->blkg))
|
|
cfq_destroy_cfqg(cfqd, cfqg);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Blk cgroup controller notification saying that blkio_group object is being
|
|
* delinked as associated cgroup object is going away. That also means that
|
|
* no new IO will come in this group. So get rid of this group as soon as
|
|
* any pending IO in the group is finished.
|
|
*
|
|
* This function is called under rcu_read_lock(). key is the rcu protected
|
|
* pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
|
|
* read lock.
|
|
*
|
|
* "key" was fetched from blkio_group under blkio_cgroup->lock. That means
|
|
* it should not be NULL as even if elevator was exiting, cgroup deltion
|
|
* path got to it first.
|
|
*/
|
|
void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
|
|
{
|
|
unsigned long flags;
|
|
struct cfq_data *cfqd = key;
|
|
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
|
|
#else /* GROUP_IOSCHED */
|
|
static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
|
|
{
|
|
return &cfqd->root_group;
|
|
}
|
|
static inline void
|
|
cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
|
|
cfqq->cfqg = cfqg;
|
|
}
|
|
|
|
static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
|
|
static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
|
|
|
|
#endif /* GROUP_IOSCHED */
|
|
|
|
/*
|
|
* The cfqd->service_trees holds all pending cfq_queue's that have
|
|
* requests waiting to be processed. It is sorted in the order that
|
|
* we will service the queues.
|
|
*/
|
|
static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
bool add_front)
|
|
{
|
|
struct rb_node **p, *parent;
|
|
struct cfq_queue *__cfqq;
|
|
unsigned long rb_key;
|
|
struct cfq_rb_root *service_tree;
|
|
int left;
|
|
int new_cfqq = 1;
|
|
int group_changed = 0;
|
|
|
|
#ifdef CONFIG_CFQ_GROUP_IOSCHED
|
|
if (!cfqd->cfq_group_isolation
|
|
&& cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
|
|
&& cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
|
|
/* Move this cfq to root group */
|
|
cfq_log_cfqq(cfqd, cfqq, "moving to root group");
|
|
if (!RB_EMPTY_NODE(&cfqq->rb_node))
|
|
cfq_group_service_tree_del(cfqd, cfqq->cfqg);
|
|
cfqq->orig_cfqg = cfqq->cfqg;
|
|
cfqq->cfqg = &cfqd->root_group;
|
|
atomic_inc(&cfqd->root_group.ref);
|
|
group_changed = 1;
|
|
} else if (!cfqd->cfq_group_isolation
|
|
&& cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
|
|
/* cfqq is sequential now needs to go to its original group */
|
|
BUG_ON(cfqq->cfqg != &cfqd->root_group);
|
|
if (!RB_EMPTY_NODE(&cfqq->rb_node))
|
|
cfq_group_service_tree_del(cfqd, cfqq->cfqg);
|
|
cfq_put_cfqg(cfqq->cfqg);
|
|
cfqq->cfqg = cfqq->orig_cfqg;
|
|
cfqq->orig_cfqg = NULL;
|
|
group_changed = 1;
|
|
cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
|
|
}
|
|
#endif
|
|
|
|
service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
|
|
cfqq_type(cfqq));
|
|
if (cfq_class_idle(cfqq)) {
|
|
rb_key = CFQ_IDLE_DELAY;
|
|
parent = rb_last(&service_tree->rb);
|
|
if (parent && parent != &cfqq->rb_node) {
|
|
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
|
|
rb_key += __cfqq->rb_key;
|
|
} else
|
|
rb_key += jiffies;
|
|
} else if (!add_front) {
|
|
/*
|
|
* Get our rb key offset. Subtract any residual slice
|
|
* value carried from last service. A negative resid
|
|
* count indicates slice overrun, and this should position
|
|
* the next service time further away in the tree.
|
|
*/
|
|
rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
|
|
rb_key -= cfqq->slice_resid;
|
|
cfqq->slice_resid = 0;
|
|
} else {
|
|
rb_key = -HZ;
|
|
__cfqq = cfq_rb_first(service_tree);
|
|
rb_key += __cfqq ? __cfqq->rb_key : jiffies;
|
|
}
|
|
|
|
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
|
|
new_cfqq = 0;
|
|
/*
|
|
* same position, nothing more to do
|
|
*/
|
|
if (rb_key == cfqq->rb_key &&
|
|
cfqq->service_tree == service_tree)
|
|
return;
|
|
|
|
cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
|
|
cfqq->service_tree = NULL;
|
|
}
|
|
|
|
left = 1;
|
|
parent = NULL;
|
|
cfqq->service_tree = service_tree;
|
|
p = &service_tree->rb.rb_node;
|
|
while (*p) {
|
|
struct rb_node **n;
|
|
|
|
parent = *p;
|
|
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
|
|
|
|
/*
|
|
* sort by key, that represents service time.
|
|
*/
|
|
if (time_before(rb_key, __cfqq->rb_key))
|
|
n = &(*p)->rb_left;
|
|
else {
|
|
n = &(*p)->rb_right;
|
|
left = 0;
|
|
}
|
|
|
|
p = n;
|
|
}
|
|
|
|
if (left)
|
|
service_tree->left = &cfqq->rb_node;
|
|
|
|
cfqq->rb_key = rb_key;
|
|
rb_link_node(&cfqq->rb_node, parent, p);
|
|
rb_insert_color(&cfqq->rb_node, &service_tree->rb);
|
|
service_tree->count++;
|
|
if ((add_front || !new_cfqq) && !group_changed)
|
|
return;
|
|
cfq_group_service_tree_add(cfqd, cfqq->cfqg);
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
|
|
sector_t sector, struct rb_node **ret_parent,
|
|
struct rb_node ***rb_link)
|
|
{
|
|
struct rb_node **p, *parent;
|
|
struct cfq_queue *cfqq = NULL;
|
|
|
|
parent = NULL;
|
|
p = &root->rb_node;
|
|
while (*p) {
|
|
struct rb_node **n;
|
|
|
|
parent = *p;
|
|
cfqq = rb_entry(parent, struct cfq_queue, p_node);
|
|
|
|
/*
|
|
* Sort strictly based on sector. Smallest to the left,
|
|
* largest to the right.
|
|
*/
|
|
if (sector > blk_rq_pos(cfqq->next_rq))
|
|
n = &(*p)->rb_right;
|
|
else if (sector < blk_rq_pos(cfqq->next_rq))
|
|
n = &(*p)->rb_left;
|
|
else
|
|
break;
|
|
p = n;
|
|
cfqq = NULL;
|
|
}
|
|
|
|
*ret_parent = parent;
|
|
if (rb_link)
|
|
*rb_link = p;
|
|
return cfqq;
|
|
}
|
|
|
|
static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
struct rb_node **p, *parent;
|
|
struct cfq_queue *__cfqq;
|
|
|
|
if (cfqq->p_root) {
|
|
rb_erase(&cfqq->p_node, cfqq->p_root);
|
|
cfqq->p_root = NULL;
|
|
}
|
|
|
|
if (cfq_class_idle(cfqq))
|
|
return;
|
|
if (!cfqq->next_rq)
|
|
return;
|
|
|
|
cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
|
|
__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
|
|
blk_rq_pos(cfqq->next_rq), &parent, &p);
|
|
if (!__cfqq) {
|
|
rb_link_node(&cfqq->p_node, parent, p);
|
|
rb_insert_color(&cfqq->p_node, cfqq->p_root);
|
|
} else
|
|
cfqq->p_root = NULL;
|
|
}
|
|
|
|
/*
|
|
* Update cfqq's position in the service tree.
|
|
*/
|
|
static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
/*
|
|
* Resorting requires the cfqq to be on the RR list already.
|
|
*/
|
|
if (cfq_cfqq_on_rr(cfqq)) {
|
|
cfq_service_tree_add(cfqd, cfqq, 0);
|
|
cfq_prio_tree_add(cfqd, cfqq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* add to busy list of queues for service, trying to be fair in ordering
|
|
* the pending list according to last request service
|
|
*/
|
|
static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
|
|
BUG_ON(cfq_cfqq_on_rr(cfqq));
|
|
cfq_mark_cfqq_on_rr(cfqq);
|
|
cfqd->busy_queues++;
|
|
|
|
cfq_resort_rr_list(cfqd, cfqq);
|
|
}
|
|
|
|
/*
|
|
* Called when the cfqq no longer has requests pending, remove it from
|
|
* the service tree.
|
|
*/
|
|
static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
|
|
BUG_ON(!cfq_cfqq_on_rr(cfqq));
|
|
cfq_clear_cfqq_on_rr(cfqq);
|
|
|
|
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
|
|
cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
|
|
cfqq->service_tree = NULL;
|
|
}
|
|
if (cfqq->p_root) {
|
|
rb_erase(&cfqq->p_node, cfqq->p_root);
|
|
cfqq->p_root = NULL;
|
|
}
|
|
|
|
cfq_group_service_tree_del(cfqd, cfqq->cfqg);
|
|
BUG_ON(!cfqd->busy_queues);
|
|
cfqd->busy_queues--;
|
|
}
|
|
|
|
/*
|
|
* rb tree support functions
|
|
*/
|
|
static void cfq_del_rq_rb(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
const int sync = rq_is_sync(rq);
|
|
|
|
BUG_ON(!cfqq->queued[sync]);
|
|
cfqq->queued[sync]--;
|
|
|
|
elv_rb_del(&cfqq->sort_list, rq);
|
|
|
|
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
|
|
/*
|
|
* Queue will be deleted from service tree when we actually
|
|
* expire it later. Right now just remove it from prio tree
|
|
* as it is empty.
|
|
*/
|
|
if (cfqq->p_root) {
|
|
rb_erase(&cfqq->p_node, cfqq->p_root);
|
|
cfqq->p_root = NULL;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void cfq_add_rq_rb(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
struct request *__alias, *prev;
|
|
|
|
cfqq->queued[rq_is_sync(rq)]++;
|
|
|
|
/*
|
|
* looks a little odd, but the first insert might return an alias.
|
|
* if that happens, put the alias on the dispatch list
|
|
*/
|
|
while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
|
|
cfq_dispatch_insert(cfqd->queue, __alias);
|
|
|
|
if (!cfq_cfqq_on_rr(cfqq))
|
|
cfq_add_cfqq_rr(cfqd, cfqq);
|
|
|
|
/*
|
|
* check if this request is a better next-serve candidate
|
|
*/
|
|
prev = cfqq->next_rq;
|
|
cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
|
|
|
|
/*
|
|
* adjust priority tree position, if ->next_rq changes
|
|
*/
|
|
if (prev != cfqq->next_rq)
|
|
cfq_prio_tree_add(cfqd, cfqq);
|
|
|
|
BUG_ON(!cfqq->next_rq);
|
|
}
|
|
|
|
static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
|
|
{
|
|
elv_rb_del(&cfqq->sort_list, rq);
|
|
cfqq->queued[rq_is_sync(rq)]--;
|
|
cfq_add_rq_rb(rq);
|
|
}
|
|
|
|
static struct request *
|
|
cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_queue *cfqq;
|
|
|
|
cic = cfq_cic_lookup(cfqd, tsk->io_context);
|
|
if (!cic)
|
|
return NULL;
|
|
|
|
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
|
|
if (cfqq) {
|
|
sector_t sector = bio->bi_sector + bio_sectors(bio);
|
|
|
|
return elv_rb_find(&cfqq->sort_list, sector);
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void cfq_activate_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
|
|
cfqd->rq_in_driver++;
|
|
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
|
|
cfqd->rq_in_driver);
|
|
|
|
cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
|
|
}
|
|
|
|
static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
|
|
WARN_ON(!cfqd->rq_in_driver);
|
|
cfqd->rq_in_driver--;
|
|
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
|
|
cfqd->rq_in_driver);
|
|
}
|
|
|
|
static void cfq_remove_request(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
if (cfqq->next_rq == rq)
|
|
cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
|
|
|
|
list_del_init(&rq->queuelist);
|
|
cfq_del_rq_rb(rq);
|
|
|
|
cfqq->cfqd->rq_queued--;
|
|
if (rq_is_meta(rq)) {
|
|
WARN_ON(!cfqq->meta_pending);
|
|
cfqq->meta_pending--;
|
|
}
|
|
}
|
|
|
|
static int cfq_merge(struct request_queue *q, struct request **req,
|
|
struct bio *bio)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct request *__rq;
|
|
|
|
__rq = cfq_find_rq_fmerge(cfqd, bio);
|
|
if (__rq && elv_rq_merge_ok(__rq, bio)) {
|
|
*req = __rq;
|
|
return ELEVATOR_FRONT_MERGE;
|
|
}
|
|
|
|
return ELEVATOR_NO_MERGE;
|
|
}
|
|
|
|
static void cfq_merged_request(struct request_queue *q, struct request *req,
|
|
int type)
|
|
{
|
|
if (type == ELEVATOR_FRONT_MERGE) {
|
|
struct cfq_queue *cfqq = RQ_CFQQ(req);
|
|
|
|
cfq_reposition_rq_rb(cfqq, req);
|
|
}
|
|
}
|
|
|
|
static void
|
|
cfq_merged_requests(struct request_queue *q, struct request *rq,
|
|
struct request *next)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
/*
|
|
* reposition in fifo if next is older than rq
|
|
*/
|
|
if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
|
|
time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
|
|
list_move(&rq->queuelist, &next->queuelist);
|
|
rq_set_fifo_time(rq, rq_fifo_time(next));
|
|
}
|
|
|
|
if (cfqq->next_rq == next)
|
|
cfqq->next_rq = rq;
|
|
cfq_remove_request(next);
|
|
}
|
|
|
|
static int cfq_allow_merge(struct request_queue *q, struct request *rq,
|
|
struct bio *bio)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_queue *cfqq;
|
|
|
|
/*
|
|
* Disallow merge of a sync bio into an async request.
|
|
*/
|
|
if (cfq_bio_sync(bio) && !rq_is_sync(rq))
|
|
return false;
|
|
|
|
/*
|
|
* Lookup the cfqq that this bio will be queued with. Allow
|
|
* merge only if rq is queued there.
|
|
*/
|
|
cic = cfq_cic_lookup(cfqd, current->io_context);
|
|
if (!cic)
|
|
return false;
|
|
|
|
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
|
|
return cfqq == RQ_CFQQ(rq);
|
|
}
|
|
|
|
static void __cfq_set_active_queue(struct cfq_data *cfqd,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
if (cfqq) {
|
|
cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
|
|
cfqd->serving_prio, cfqd->serving_type);
|
|
cfqq->slice_start = 0;
|
|
cfqq->dispatch_start = jiffies;
|
|
cfqq->allocated_slice = 0;
|
|
cfqq->slice_end = 0;
|
|
cfqq->slice_dispatch = 0;
|
|
cfqq->nr_sectors = 0;
|
|
|
|
cfq_clear_cfqq_wait_request(cfqq);
|
|
cfq_clear_cfqq_must_dispatch(cfqq);
|
|
cfq_clear_cfqq_must_alloc_slice(cfqq);
|
|
cfq_clear_cfqq_fifo_expire(cfqq);
|
|
cfq_mark_cfqq_slice_new(cfqq);
|
|
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
}
|
|
|
|
cfqd->active_queue = cfqq;
|
|
}
|
|
|
|
/*
|
|
* current cfqq expired its slice (or was too idle), select new one
|
|
*/
|
|
static void
|
|
__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
bool timed_out)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
|
|
|
|
if (cfq_cfqq_wait_request(cfqq))
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
|
|
cfq_clear_cfqq_wait_request(cfqq);
|
|
cfq_clear_cfqq_wait_busy(cfqq);
|
|
|
|
/*
|
|
* If this cfqq is shared between multiple processes, check to
|
|
* make sure that those processes are still issuing I/Os within
|
|
* the mean seek distance. If not, it may be time to break the
|
|
* queues apart again.
|
|
*/
|
|
if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
|
|
cfq_mark_cfqq_split_coop(cfqq);
|
|
|
|
/*
|
|
* store what was left of this slice, if the queue idled/timed out
|
|
*/
|
|
if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
|
|
cfqq->slice_resid = cfqq->slice_end - jiffies;
|
|
cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
|
|
}
|
|
|
|
cfq_group_served(cfqd, cfqq->cfqg, cfqq);
|
|
|
|
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
cfq_del_cfqq_rr(cfqd, cfqq);
|
|
|
|
cfq_resort_rr_list(cfqd, cfqq);
|
|
|
|
if (cfqq == cfqd->active_queue)
|
|
cfqd->active_queue = NULL;
|
|
|
|
if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active)
|
|
cfqd->grp_service_tree.active = NULL;
|
|
|
|
if (cfqd->active_cic) {
|
|
put_io_context(cfqd->active_cic->ioc);
|
|
cfqd->active_cic = NULL;
|
|
}
|
|
}
|
|
|
|
static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
|
|
{
|
|
struct cfq_queue *cfqq = cfqd->active_queue;
|
|
|
|
if (cfqq)
|
|
__cfq_slice_expired(cfqd, cfqq, timed_out);
|
|
}
|
|
|
|
/*
|
|
* Get next queue for service. Unless we have a queue preemption,
|
|
* we'll simply select the first cfqq in the service tree.
|
|
*/
|
|
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_rb_root *service_tree =
|
|
service_tree_for(cfqd->serving_group, cfqd->serving_prio,
|
|
cfqd->serving_type);
|
|
|
|
if (!cfqd->rq_queued)
|
|
return NULL;
|
|
|
|
/* There is nothing to dispatch */
|
|
if (!service_tree)
|
|
return NULL;
|
|
if (RB_EMPTY_ROOT(&service_tree->rb))
|
|
return NULL;
|
|
return cfq_rb_first(service_tree);
|
|
}
|
|
|
|
static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_group *cfqg;
|
|
struct cfq_queue *cfqq;
|
|
int i, j;
|
|
struct cfq_rb_root *st;
|
|
|
|
if (!cfqd->rq_queued)
|
|
return NULL;
|
|
|
|
cfqg = cfq_get_next_cfqg(cfqd);
|
|
if (!cfqg)
|
|
return NULL;
|
|
|
|
for_each_cfqg_st(cfqg, i, j, st)
|
|
if ((cfqq = cfq_rb_first(st)) != NULL)
|
|
return cfqq;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Get and set a new active queue for service.
|
|
*/
|
|
static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
if (!cfqq)
|
|
cfqq = cfq_get_next_queue(cfqd);
|
|
|
|
__cfq_set_active_queue(cfqd, cfqq);
|
|
return cfqq;
|
|
}
|
|
|
|
static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
|
|
struct request *rq)
|
|
{
|
|
if (blk_rq_pos(rq) >= cfqd->last_position)
|
|
return blk_rq_pos(rq) - cfqd->last_position;
|
|
else
|
|
return cfqd->last_position - blk_rq_pos(rq);
|
|
}
|
|
|
|
static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct request *rq)
|
|
{
|
|
return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
|
|
}
|
|
|
|
static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
|
|
struct cfq_queue *cur_cfqq)
|
|
{
|
|
struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
|
|
struct rb_node *parent, *node;
|
|
struct cfq_queue *__cfqq;
|
|
sector_t sector = cfqd->last_position;
|
|
|
|
if (RB_EMPTY_ROOT(root))
|
|
return NULL;
|
|
|
|
/*
|
|
* First, if we find a request starting at the end of the last
|
|
* request, choose it.
|
|
*/
|
|
__cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
|
|
if (__cfqq)
|
|
return __cfqq;
|
|
|
|
/*
|
|
* If the exact sector wasn't found, the parent of the NULL leaf
|
|
* will contain the closest sector.
|
|
*/
|
|
__cfqq = rb_entry(parent, struct cfq_queue, p_node);
|
|
if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
|
|
return __cfqq;
|
|
|
|
if (blk_rq_pos(__cfqq->next_rq) < sector)
|
|
node = rb_next(&__cfqq->p_node);
|
|
else
|
|
node = rb_prev(&__cfqq->p_node);
|
|
if (!node)
|
|
return NULL;
|
|
|
|
__cfqq = rb_entry(node, struct cfq_queue, p_node);
|
|
if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
|
|
return __cfqq;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* cfqd - obvious
|
|
* cur_cfqq - passed in so that we don't decide that the current queue is
|
|
* closely cooperating with itself.
|
|
*
|
|
* So, basically we're assuming that that cur_cfqq has dispatched at least
|
|
* one request, and that cfqd->last_position reflects a position on the disk
|
|
* associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
|
|
* assumption.
|
|
*/
|
|
static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
|
|
struct cfq_queue *cur_cfqq)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
|
|
if (cfq_class_idle(cur_cfqq))
|
|
return NULL;
|
|
if (!cfq_cfqq_sync(cur_cfqq))
|
|
return NULL;
|
|
if (CFQQ_SEEKY(cur_cfqq))
|
|
return NULL;
|
|
|
|
/*
|
|
* Don't search priority tree if it's the only queue in the group.
|
|
*/
|
|
if (cur_cfqq->cfqg->nr_cfqq == 1)
|
|
return NULL;
|
|
|
|
/*
|
|
* We should notice if some of the queues are cooperating, eg
|
|
* working closely on the same area of the disk. In that case,
|
|
* we can group them together and don't waste time idling.
|
|
*/
|
|
cfqq = cfqq_close(cfqd, cur_cfqq);
|
|
if (!cfqq)
|
|
return NULL;
|
|
|
|
/* If new queue belongs to different cfq_group, don't choose it */
|
|
if (cur_cfqq->cfqg != cfqq->cfqg)
|
|
return NULL;
|
|
|
|
/*
|
|
* It only makes sense to merge sync queues.
|
|
*/
|
|
if (!cfq_cfqq_sync(cfqq))
|
|
return NULL;
|
|
if (CFQQ_SEEKY(cfqq))
|
|
return NULL;
|
|
|
|
/*
|
|
* Do not merge queues of different priority classes
|
|
*/
|
|
if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
|
|
return NULL;
|
|
|
|
return cfqq;
|
|
}
|
|
|
|
/*
|
|
* Determine whether we should enforce idle window for this queue.
|
|
*/
|
|
|
|
static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
enum wl_prio_t prio = cfqq_prio(cfqq);
|
|
struct cfq_rb_root *service_tree = cfqq->service_tree;
|
|
|
|
BUG_ON(!service_tree);
|
|
BUG_ON(!service_tree->count);
|
|
|
|
/* We never do for idle class queues. */
|
|
if (prio == IDLE_WORKLOAD)
|
|
return false;
|
|
|
|
/* We do for queues that were marked with idle window flag. */
|
|
if (cfq_cfqq_idle_window(cfqq) &&
|
|
!(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
|
|
return true;
|
|
|
|
/*
|
|
* Otherwise, we do only if they are the last ones
|
|
* in their service tree.
|
|
*/
|
|
if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
|
|
return 1;
|
|
cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
|
|
service_tree->count);
|
|
return 0;
|
|
}
|
|
|
|
static void cfq_arm_slice_timer(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq = cfqd->active_queue;
|
|
struct cfq_io_context *cic;
|
|
unsigned long sl;
|
|
|
|
/*
|
|
* SSD device without seek penalty, disable idling. But only do so
|
|
* for devices that support queuing, otherwise we still have a problem
|
|
* with sync vs async workloads.
|
|
*/
|
|
if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
|
|
return;
|
|
|
|
WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
|
|
WARN_ON(cfq_cfqq_slice_new(cfqq));
|
|
|
|
/*
|
|
* idle is disabled, either manually or by past process history
|
|
*/
|
|
if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
|
|
return;
|
|
|
|
/*
|
|
* still active requests from this queue, don't idle
|
|
*/
|
|
if (cfqq->dispatched)
|
|
return;
|
|
|
|
/*
|
|
* task has exited, don't wait
|
|
*/
|
|
cic = cfqd->active_cic;
|
|
if (!cic || !atomic_read(&cic->ioc->nr_tasks))
|
|
return;
|
|
|
|
/*
|
|
* If our average think time is larger than the remaining time
|
|
* slice, then don't idle. This avoids overrunning the allotted
|
|
* time slice.
|
|
*/
|
|
if (sample_valid(cic->ttime_samples) &&
|
|
(cfqq->slice_end - jiffies < cic->ttime_mean)) {
|
|
cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
|
|
cic->ttime_mean);
|
|
return;
|
|
}
|
|
|
|
cfq_mark_cfqq_wait_request(cfqq);
|
|
|
|
sl = cfqd->cfq_slice_idle;
|
|
|
|
mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
|
|
cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
|
|
}
|
|
|
|
/*
|
|
* Move request from internal lists to the request queue dispatch list.
|
|
*/
|
|
static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
|
|
|
|
cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
|
|
cfq_remove_request(rq);
|
|
cfqq->dispatched++;
|
|
elv_dispatch_sort(q, rq);
|
|
|
|
cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
|
|
cfqq->nr_sectors += blk_rq_sectors(rq);
|
|
}
|
|
|
|
/*
|
|
* return expired entry, or NULL to just start from scratch in rbtree
|
|
*/
|
|
static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
|
|
{
|
|
struct request *rq = NULL;
|
|
|
|
if (cfq_cfqq_fifo_expire(cfqq))
|
|
return NULL;
|
|
|
|
cfq_mark_cfqq_fifo_expire(cfqq);
|
|
|
|
if (list_empty(&cfqq->fifo))
|
|
return NULL;
|
|
|
|
rq = rq_entry_fifo(cfqq->fifo.next);
|
|
if (time_before(jiffies, rq_fifo_time(rq)))
|
|
rq = NULL;
|
|
|
|
cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
|
|
return rq;
|
|
}
|
|
|
|
static inline int
|
|
cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
const int base_rq = cfqd->cfq_slice_async_rq;
|
|
|
|
WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
|
|
|
|
return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
|
|
}
|
|
|
|
/*
|
|
* Must be called with the queue_lock held.
|
|
*/
|
|
static int cfqq_process_refs(struct cfq_queue *cfqq)
|
|
{
|
|
int process_refs, io_refs;
|
|
|
|
io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
|
|
process_refs = atomic_read(&cfqq->ref) - io_refs;
|
|
BUG_ON(process_refs < 0);
|
|
return process_refs;
|
|
}
|
|
|
|
static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
|
|
{
|
|
int process_refs, new_process_refs;
|
|
struct cfq_queue *__cfqq;
|
|
|
|
/* Avoid a circular list and skip interim queue merges */
|
|
while ((__cfqq = new_cfqq->new_cfqq)) {
|
|
if (__cfqq == cfqq)
|
|
return;
|
|
new_cfqq = __cfqq;
|
|
}
|
|
|
|
process_refs = cfqq_process_refs(cfqq);
|
|
/*
|
|
* If the process for the cfqq has gone away, there is no
|
|
* sense in merging the queues.
|
|
*/
|
|
if (process_refs == 0)
|
|
return;
|
|
|
|
/*
|
|
* Merge in the direction of the lesser amount of work.
|
|
*/
|
|
new_process_refs = cfqq_process_refs(new_cfqq);
|
|
if (new_process_refs >= process_refs) {
|
|
cfqq->new_cfqq = new_cfqq;
|
|
atomic_add(process_refs, &new_cfqq->ref);
|
|
} else {
|
|
new_cfqq->new_cfqq = cfqq;
|
|
atomic_add(new_process_refs, &cfqq->ref);
|
|
}
|
|
}
|
|
|
|
static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
|
|
struct cfq_group *cfqg, enum wl_prio_t prio)
|
|
{
|
|
struct cfq_queue *queue;
|
|
int i;
|
|
bool key_valid = false;
|
|
unsigned long lowest_key = 0;
|
|
enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
|
|
|
|
for (i = 0; i <= SYNC_WORKLOAD; ++i) {
|
|
/* select the one with lowest rb_key */
|
|
queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
|
|
if (queue &&
|
|
(!key_valid || time_before(queue->rb_key, lowest_key))) {
|
|
lowest_key = queue->rb_key;
|
|
cur_best = i;
|
|
key_valid = true;
|
|
}
|
|
}
|
|
|
|
return cur_best;
|
|
}
|
|
|
|
static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
|
|
{
|
|
unsigned slice;
|
|
unsigned count;
|
|
struct cfq_rb_root *st;
|
|
unsigned group_slice;
|
|
|
|
if (!cfqg) {
|
|
cfqd->serving_prio = IDLE_WORKLOAD;
|
|
cfqd->workload_expires = jiffies + 1;
|
|
return;
|
|
}
|
|
|
|
/* Choose next priority. RT > BE > IDLE */
|
|
if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
|
|
cfqd->serving_prio = RT_WORKLOAD;
|
|
else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
|
|
cfqd->serving_prio = BE_WORKLOAD;
|
|
else {
|
|
cfqd->serving_prio = IDLE_WORKLOAD;
|
|
cfqd->workload_expires = jiffies + 1;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* For RT and BE, we have to choose also the type
|
|
* (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
|
|
* expiration time
|
|
*/
|
|
st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
|
|
count = st->count;
|
|
|
|
/*
|
|
* check workload expiration, and that we still have other queues ready
|
|
*/
|
|
if (count && !time_after(jiffies, cfqd->workload_expires))
|
|
return;
|
|
|
|
/* otherwise select new workload type */
|
|
cfqd->serving_type =
|
|
cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
|
|
st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
|
|
count = st->count;
|
|
|
|
/*
|
|
* the workload slice is computed as a fraction of target latency
|
|
* proportional to the number of queues in that workload, over
|
|
* all the queues in the same priority class
|
|
*/
|
|
group_slice = cfq_group_slice(cfqd, cfqg);
|
|
|
|
slice = group_slice * count /
|
|
max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
|
|
cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
|
|
|
|
if (cfqd->serving_type == ASYNC_WORKLOAD) {
|
|
unsigned int tmp;
|
|
|
|
/*
|
|
* Async queues are currently system wide. Just taking
|
|
* proportion of queues with-in same group will lead to higher
|
|
* async ratio system wide as generally root group is going
|
|
* to have higher weight. A more accurate thing would be to
|
|
* calculate system wide asnc/sync ratio.
|
|
*/
|
|
tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
|
|
tmp = tmp/cfqd->busy_queues;
|
|
slice = min_t(unsigned, slice, tmp);
|
|
|
|
/* async workload slice is scaled down according to
|
|
* the sync/async slice ratio. */
|
|
slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
|
|
} else
|
|
/* sync workload slice is at least 2 * cfq_slice_idle */
|
|
slice = max(slice, 2 * cfqd->cfq_slice_idle);
|
|
|
|
slice = max_t(unsigned, slice, CFQ_MIN_TT);
|
|
cfq_log(cfqd, "workload slice:%d", slice);
|
|
cfqd->workload_expires = jiffies + slice;
|
|
cfqd->noidle_tree_requires_idle = false;
|
|
}
|
|
|
|
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_rb_root *st = &cfqd->grp_service_tree;
|
|
struct cfq_group *cfqg;
|
|
|
|
if (RB_EMPTY_ROOT(&st->rb))
|
|
return NULL;
|
|
cfqg = cfq_rb_first_group(st);
|
|
st->active = &cfqg->rb_node;
|
|
update_min_vdisktime(st);
|
|
return cfqg;
|
|
}
|
|
|
|
static void cfq_choose_cfqg(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
|
|
|
|
cfqd->serving_group = cfqg;
|
|
|
|
/* Restore the workload type data */
|
|
if (cfqg->saved_workload_slice) {
|
|
cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
|
|
cfqd->serving_type = cfqg->saved_workload;
|
|
cfqd->serving_prio = cfqg->saved_serving_prio;
|
|
} else
|
|
cfqd->workload_expires = jiffies - 1;
|
|
|
|
choose_service_tree(cfqd, cfqg);
|
|
}
|
|
|
|
/*
|
|
* Select a queue for service. If we have a current active queue,
|
|
* check whether to continue servicing it, or retrieve and set a new one.
|
|
*/
|
|
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq, *new_cfqq = NULL;
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (!cfqq)
|
|
goto new_queue;
|
|
|
|
if (!cfqd->rq_queued)
|
|
return NULL;
|
|
|
|
/*
|
|
* We were waiting for group to get backlogged. Expire the queue
|
|
*/
|
|
if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
goto expire;
|
|
|
|
/*
|
|
* The active queue has run out of time, expire it and select new.
|
|
*/
|
|
if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
|
|
/*
|
|
* If slice had not expired at the completion of last request
|
|
* we might not have turned on wait_busy flag. Don't expire
|
|
* the queue yet. Allow the group to get backlogged.
|
|
*
|
|
* The very fact that we have used the slice, that means we
|
|
* have been idling all along on this queue and it should be
|
|
* ok to wait for this request to complete.
|
|
*/
|
|
if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
|
|
&& cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
|
|
cfqq = NULL;
|
|
goto keep_queue;
|
|
} else
|
|
goto expire;
|
|
}
|
|
|
|
/*
|
|
* The active queue has requests and isn't expired, allow it to
|
|
* dispatch.
|
|
*/
|
|
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
goto keep_queue;
|
|
|
|
/*
|
|
* If another queue has a request waiting within our mean seek
|
|
* distance, let it run. The expire code will check for close
|
|
* cooperators and put the close queue at the front of the service
|
|
* tree. If possible, merge the expiring queue with the new cfqq.
|
|
*/
|
|
new_cfqq = cfq_close_cooperator(cfqd, cfqq);
|
|
if (new_cfqq) {
|
|
if (!cfqq->new_cfqq)
|
|
cfq_setup_merge(cfqq, new_cfqq);
|
|
goto expire;
|
|
}
|
|
|
|
/*
|
|
* No requests pending. If the active queue still has requests in
|
|
* flight or is idling for a new request, allow either of these
|
|
* conditions to happen (or time out) before selecting a new queue.
|
|
*/
|
|
if (timer_pending(&cfqd->idle_slice_timer) ||
|
|
(cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
|
|
cfqq = NULL;
|
|
goto keep_queue;
|
|
}
|
|
|
|
expire:
|
|
cfq_slice_expired(cfqd, 0);
|
|
new_queue:
|
|
/*
|
|
* Current queue expired. Check if we have to switch to a new
|
|
* service tree
|
|
*/
|
|
if (!new_cfqq)
|
|
cfq_choose_cfqg(cfqd);
|
|
|
|
cfqq = cfq_set_active_queue(cfqd, new_cfqq);
|
|
keep_queue:
|
|
return cfqq;
|
|
}
|
|
|
|
static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
|
|
{
|
|
int dispatched = 0;
|
|
|
|
while (cfqq->next_rq) {
|
|
cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
|
|
dispatched++;
|
|
}
|
|
|
|
BUG_ON(!list_empty(&cfqq->fifo));
|
|
|
|
/* By default cfqq is not expired if it is empty. Do it explicitly */
|
|
__cfq_slice_expired(cfqq->cfqd, cfqq, 0);
|
|
return dispatched;
|
|
}
|
|
|
|
/*
|
|
* Drain our current requests. Used for barriers and when switching
|
|
* io schedulers on-the-fly.
|
|
*/
|
|
static int cfq_forced_dispatch(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
int dispatched = 0;
|
|
|
|
/* Expire the timeslice of the current active queue first */
|
|
cfq_slice_expired(cfqd, 0);
|
|
while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
|
|
__cfq_set_active_queue(cfqd, cfqq);
|
|
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
|
|
}
|
|
|
|
BUG_ON(cfqd->busy_queues);
|
|
|
|
cfq_log(cfqd, "forced_dispatch=%d", dispatched);
|
|
return dispatched;
|
|
}
|
|
|
|
static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
/* the queue hasn't finished any request, can't estimate */
|
|
if (cfq_cfqq_slice_new(cfqq))
|
|
return 1;
|
|
if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
|
|
cfqq->slice_end))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
unsigned int max_dispatch;
|
|
|
|
/*
|
|
* Drain async requests before we start sync IO
|
|
*/
|
|
if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
|
|
return false;
|
|
|
|
/*
|
|
* If this is an async queue and we have sync IO in flight, let it wait
|
|
*/
|
|
if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
|
|
return false;
|
|
|
|
max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
|
|
if (cfq_class_idle(cfqq))
|
|
max_dispatch = 1;
|
|
|
|
/*
|
|
* Does this cfqq already have too much IO in flight?
|
|
*/
|
|
if (cfqq->dispatched >= max_dispatch) {
|
|
/*
|
|
* idle queue must always only have a single IO in flight
|
|
*/
|
|
if (cfq_class_idle(cfqq))
|
|
return false;
|
|
|
|
/*
|
|
* We have other queues, don't allow more IO from this one
|
|
*/
|
|
if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq))
|
|
return false;
|
|
|
|
/*
|
|
* Sole queue user, no limit
|
|
*/
|
|
if (cfqd->busy_queues == 1)
|
|
max_dispatch = -1;
|
|
else
|
|
/*
|
|
* Normally we start throttling cfqq when cfq_quantum/2
|
|
* requests have been dispatched. But we can drive
|
|
* deeper queue depths at the beginning of slice
|
|
* subjected to upper limit of cfq_quantum.
|
|
* */
|
|
max_dispatch = cfqd->cfq_quantum;
|
|
}
|
|
|
|
/*
|
|
* Async queues must wait a bit before being allowed dispatch.
|
|
* We also ramp up the dispatch depth gradually for async IO,
|
|
* based on the last sync IO we serviced
|
|
*/
|
|
if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
|
|
unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
|
|
unsigned int depth;
|
|
|
|
depth = last_sync / cfqd->cfq_slice[1];
|
|
if (!depth && !cfqq->dispatched)
|
|
depth = 1;
|
|
if (depth < max_dispatch)
|
|
max_dispatch = depth;
|
|
}
|
|
|
|
/*
|
|
* If we're below the current max, allow a dispatch
|
|
*/
|
|
return cfqq->dispatched < max_dispatch;
|
|
}
|
|
|
|
/*
|
|
* Dispatch a request from cfqq, moving them to the request queue
|
|
* dispatch list.
|
|
*/
|
|
static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
struct request *rq;
|
|
|
|
BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
|
|
|
|
if (!cfq_may_dispatch(cfqd, cfqq))
|
|
return false;
|
|
|
|
/*
|
|
* follow expired path, else get first next available
|
|
*/
|
|
rq = cfq_check_fifo(cfqq);
|
|
if (!rq)
|
|
rq = cfqq->next_rq;
|
|
|
|
/*
|
|
* insert request into driver dispatch list
|
|
*/
|
|
cfq_dispatch_insert(cfqd->queue, rq);
|
|
|
|
if (!cfqd->active_cic) {
|
|
struct cfq_io_context *cic = RQ_CIC(rq);
|
|
|
|
atomic_long_inc(&cic->ioc->refcount);
|
|
cfqd->active_cic = cic;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Find the cfqq that we need to service and move a request from that to the
|
|
* dispatch list
|
|
*/
|
|
static int cfq_dispatch_requests(struct request_queue *q, int force)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq;
|
|
|
|
if (!cfqd->busy_queues)
|
|
return 0;
|
|
|
|
if (unlikely(force))
|
|
return cfq_forced_dispatch(cfqd);
|
|
|
|
cfqq = cfq_select_queue(cfqd);
|
|
if (!cfqq)
|
|
return 0;
|
|
|
|
/*
|
|
* Dispatch a request from this cfqq, if it is allowed
|
|
*/
|
|
if (!cfq_dispatch_request(cfqd, cfqq))
|
|
return 0;
|
|
|
|
cfqq->slice_dispatch++;
|
|
cfq_clear_cfqq_must_dispatch(cfqq);
|
|
|
|
/*
|
|
* expire an async queue immediately if it has used up its slice. idle
|
|
* queue always expire after 1 dispatch round.
|
|
*/
|
|
if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
|
|
cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
|
|
cfq_class_idle(cfqq))) {
|
|
cfqq->slice_end = jiffies + 1;
|
|
cfq_slice_expired(cfqd, 0);
|
|
}
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* task holds one reference to the queue, dropped when task exits. each rq
|
|
* in-flight on this queue also holds a reference, dropped when rq is freed.
|
|
*
|
|
* Each cfq queue took a reference on the parent group. Drop it now.
|
|
* queue lock must be held here.
|
|
*/
|
|
static void cfq_put_queue(struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
struct cfq_group *cfqg, *orig_cfqg;
|
|
|
|
BUG_ON(atomic_read(&cfqq->ref) <= 0);
|
|
|
|
if (!atomic_dec_and_test(&cfqq->ref))
|
|
return;
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "put_queue");
|
|
BUG_ON(rb_first(&cfqq->sort_list));
|
|
BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
|
|
cfqg = cfqq->cfqg;
|
|
orig_cfqg = cfqq->orig_cfqg;
|
|
|
|
if (unlikely(cfqd->active_queue == cfqq)) {
|
|
__cfq_slice_expired(cfqd, cfqq, 0);
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
BUG_ON(cfq_cfqq_on_rr(cfqq));
|
|
kmem_cache_free(cfq_pool, cfqq);
|
|
cfq_put_cfqg(cfqg);
|
|
if (orig_cfqg)
|
|
cfq_put_cfqg(orig_cfqg);
|
|
}
|
|
|
|
/*
|
|
* Must always be called with the rcu_read_lock() held
|
|
*/
|
|
static void
|
|
__call_for_each_cic(struct io_context *ioc,
|
|
void (*func)(struct io_context *, struct cfq_io_context *))
|
|
{
|
|
struct cfq_io_context *cic;
|
|
struct hlist_node *n;
|
|
|
|
hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
|
|
func(ioc, cic);
|
|
}
|
|
|
|
/*
|
|
* Call func for each cic attached to this ioc.
|
|
*/
|
|
static void
|
|
call_for_each_cic(struct io_context *ioc,
|
|
void (*func)(struct io_context *, struct cfq_io_context *))
|
|
{
|
|
rcu_read_lock();
|
|
__call_for_each_cic(ioc, func);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static void cfq_cic_free_rcu(struct rcu_head *head)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
|
|
cic = container_of(head, struct cfq_io_context, rcu_head);
|
|
|
|
kmem_cache_free(cfq_ioc_pool, cic);
|
|
elv_ioc_count_dec(cfq_ioc_count);
|
|
|
|
if (ioc_gone) {
|
|
/*
|
|
* CFQ scheduler is exiting, grab exit lock and check
|
|
* the pending io context count. If it hits zero,
|
|
* complete ioc_gone and set it back to NULL
|
|
*/
|
|
spin_lock(&ioc_gone_lock);
|
|
if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
|
|
complete(ioc_gone);
|
|
ioc_gone = NULL;
|
|
}
|
|
spin_unlock(&ioc_gone_lock);
|
|
}
|
|
}
|
|
|
|
static void cfq_cic_free(struct cfq_io_context *cic)
|
|
{
|
|
call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
|
|
}
|
|
|
|
static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
|
|
{
|
|
unsigned long flags;
|
|
|
|
BUG_ON(!cic->dead_key);
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
radix_tree_delete(&ioc->radix_root, cic->dead_key);
|
|
hlist_del_rcu(&cic->cic_list);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
cfq_cic_free(cic);
|
|
}
|
|
|
|
/*
|
|
* Must be called with rcu_read_lock() held or preemption otherwise disabled.
|
|
* Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
|
|
* and ->trim() which is called with the task lock held
|
|
*/
|
|
static void cfq_free_io_context(struct io_context *ioc)
|
|
{
|
|
/*
|
|
* ioc->refcount is zero here, or we are called from elv_unregister(),
|
|
* so no more cic's are allowed to be linked into this ioc. So it
|
|
* should be ok to iterate over the known list, we will see all cic's
|
|
* since no new ones are added.
|
|
*/
|
|
__call_for_each_cic(ioc, cic_free_func);
|
|
}
|
|
|
|
static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_queue *__cfqq, *next;
|
|
|
|
if (unlikely(cfqq == cfqd->active_queue)) {
|
|
__cfq_slice_expired(cfqd, cfqq, 0);
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
/*
|
|
* If this queue was scheduled to merge with another queue, be
|
|
* sure to drop the reference taken on that queue (and others in
|
|
* the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
|
|
*/
|
|
__cfqq = cfqq->new_cfqq;
|
|
while (__cfqq) {
|
|
if (__cfqq == cfqq) {
|
|
WARN(1, "cfqq->new_cfqq loop detected\n");
|
|
break;
|
|
}
|
|
next = __cfqq->new_cfqq;
|
|
cfq_put_queue(__cfqq);
|
|
__cfqq = next;
|
|
}
|
|
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
|
|
static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
struct io_context *ioc = cic->ioc;
|
|
|
|
list_del_init(&cic->queue_list);
|
|
|
|
/*
|
|
* Make sure key == NULL is seen for dead queues
|
|
*/
|
|
smp_wmb();
|
|
cic->dead_key = (unsigned long) cic->key;
|
|
cic->key = NULL;
|
|
|
|
if (ioc->ioc_data == cic)
|
|
rcu_assign_pointer(ioc->ioc_data, NULL);
|
|
|
|
if (cic->cfqq[BLK_RW_ASYNC]) {
|
|
cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
|
|
cic->cfqq[BLK_RW_ASYNC] = NULL;
|
|
}
|
|
|
|
if (cic->cfqq[BLK_RW_SYNC]) {
|
|
cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
|
|
cic->cfqq[BLK_RW_SYNC] = NULL;
|
|
}
|
|
}
|
|
|
|
static void cfq_exit_single_io_context(struct io_context *ioc,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_data *cfqd = cic->key;
|
|
|
|
if (cfqd) {
|
|
struct request_queue *q = cfqd->queue;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
/*
|
|
* Ensure we get a fresh copy of the ->key to prevent
|
|
* race between exiting task and queue
|
|
*/
|
|
smp_read_barrier_depends();
|
|
if (cic->key)
|
|
__cfq_exit_single_io_context(cfqd, cic);
|
|
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The process that ioc belongs to has exited, we need to clean up
|
|
* and put the internal structures we have that belongs to that process.
|
|
*/
|
|
static void cfq_exit_io_context(struct io_context *ioc)
|
|
{
|
|
call_for_each_cic(ioc, cfq_exit_single_io_context);
|
|
}
|
|
|
|
static struct cfq_io_context *
|
|
cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
|
|
cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
|
|
cfqd->queue->node);
|
|
if (cic) {
|
|
cic->last_end_request = jiffies;
|
|
INIT_LIST_HEAD(&cic->queue_list);
|
|
INIT_HLIST_NODE(&cic->cic_list);
|
|
cic->dtor = cfq_free_io_context;
|
|
cic->exit = cfq_exit_io_context;
|
|
elv_ioc_count_inc(cfq_ioc_count);
|
|
}
|
|
|
|
return cic;
|
|
}
|
|
|
|
static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
int ioprio_class;
|
|
|
|
if (!cfq_cfqq_prio_changed(cfqq))
|
|
return;
|
|
|
|
ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
|
|
switch (ioprio_class) {
|
|
default:
|
|
printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
|
|
case IOPRIO_CLASS_NONE:
|
|
/*
|
|
* no prio set, inherit CPU scheduling settings
|
|
*/
|
|
cfqq->ioprio = task_nice_ioprio(tsk);
|
|
cfqq->ioprio_class = task_nice_ioclass(tsk);
|
|
break;
|
|
case IOPRIO_CLASS_RT:
|
|
cfqq->ioprio = task_ioprio(ioc);
|
|
cfqq->ioprio_class = IOPRIO_CLASS_RT;
|
|
break;
|
|
case IOPRIO_CLASS_BE:
|
|
cfqq->ioprio = task_ioprio(ioc);
|
|
cfqq->ioprio_class = IOPRIO_CLASS_BE;
|
|
break;
|
|
case IOPRIO_CLASS_IDLE:
|
|
cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
|
|
cfqq->ioprio = 7;
|
|
cfq_clear_cfqq_idle_window(cfqq);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* keep track of original prio settings in case we have to temporarily
|
|
* elevate the priority of this queue
|
|
*/
|
|
cfqq->org_ioprio = cfqq->ioprio;
|
|
cfqq->org_ioprio_class = cfqq->ioprio_class;
|
|
cfq_clear_cfqq_prio_changed(cfqq);
|
|
}
|
|
|
|
static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_data *cfqd = cic->key;
|
|
struct cfq_queue *cfqq;
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!cfqd))
|
|
return;
|
|
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
|
|
cfqq = cic->cfqq[BLK_RW_ASYNC];
|
|
if (cfqq) {
|
|
struct cfq_queue *new_cfqq;
|
|
new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
|
|
GFP_ATOMIC);
|
|
if (new_cfqq) {
|
|
cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
}
|
|
|
|
cfqq = cic->cfqq[BLK_RW_SYNC];
|
|
if (cfqq)
|
|
cfq_mark_cfqq_prio_changed(cfqq);
|
|
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
|
|
static void cfq_ioc_set_ioprio(struct io_context *ioc)
|
|
{
|
|
call_for_each_cic(ioc, changed_ioprio);
|
|
ioc->ioprio_changed = 0;
|
|
}
|
|
|
|
static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
pid_t pid, bool is_sync)
|
|
{
|
|
RB_CLEAR_NODE(&cfqq->rb_node);
|
|
RB_CLEAR_NODE(&cfqq->p_node);
|
|
INIT_LIST_HEAD(&cfqq->fifo);
|
|
|
|
atomic_set(&cfqq->ref, 0);
|
|
cfqq->cfqd = cfqd;
|
|
|
|
cfq_mark_cfqq_prio_changed(cfqq);
|
|
|
|
if (is_sync) {
|
|
if (!cfq_class_idle(cfqq))
|
|
cfq_mark_cfqq_idle_window(cfqq);
|
|
cfq_mark_cfqq_sync(cfqq);
|
|
}
|
|
cfqq->pid = pid;
|
|
}
|
|
|
|
#ifdef CONFIG_CFQ_GROUP_IOSCHED
|
|
static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
|
|
struct cfq_data *cfqd = cic->key;
|
|
unsigned long flags;
|
|
struct request_queue *q;
|
|
|
|
if (unlikely(!cfqd))
|
|
return;
|
|
|
|
q = cfqd->queue;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
if (sync_cfqq) {
|
|
/*
|
|
* Drop reference to sync queue. A new sync queue will be
|
|
* assigned in new group upon arrival of a fresh request.
|
|
*/
|
|
cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
|
|
cic_set_cfqq(cic, NULL, 1);
|
|
cfq_put_queue(sync_cfqq);
|
|
}
|
|
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
|
|
static void cfq_ioc_set_cgroup(struct io_context *ioc)
|
|
{
|
|
call_for_each_cic(ioc, changed_cgroup);
|
|
ioc->cgroup_changed = 0;
|
|
}
|
|
#endif /* CONFIG_CFQ_GROUP_IOSCHED */
|
|
|
|
static struct cfq_queue *
|
|
cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
|
|
struct io_context *ioc, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_queue *cfqq, *new_cfqq = NULL;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_group *cfqg;
|
|
|
|
retry:
|
|
cfqg = cfq_get_cfqg(cfqd, 1);
|
|
cic = cfq_cic_lookup(cfqd, ioc);
|
|
/* cic always exists here */
|
|
cfqq = cic_to_cfqq(cic, is_sync);
|
|
|
|
/*
|
|
* Always try a new alloc if we fell back to the OOM cfqq
|
|
* originally, since it should just be a temporary situation.
|
|
*/
|
|
if (!cfqq || cfqq == &cfqd->oom_cfqq) {
|
|
cfqq = NULL;
|
|
if (new_cfqq) {
|
|
cfqq = new_cfqq;
|
|
new_cfqq = NULL;
|
|
} else if (gfp_mask & __GFP_WAIT) {
|
|
spin_unlock_irq(cfqd->queue->queue_lock);
|
|
new_cfqq = kmem_cache_alloc_node(cfq_pool,
|
|
gfp_mask | __GFP_ZERO,
|
|
cfqd->queue->node);
|
|
spin_lock_irq(cfqd->queue->queue_lock);
|
|
if (new_cfqq)
|
|
goto retry;
|
|
} else {
|
|
cfqq = kmem_cache_alloc_node(cfq_pool,
|
|
gfp_mask | __GFP_ZERO,
|
|
cfqd->queue->node);
|
|
}
|
|
|
|
if (cfqq) {
|
|
cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
|
|
cfq_init_prio_data(cfqq, ioc);
|
|
cfq_link_cfqq_cfqg(cfqq, cfqg);
|
|
cfq_log_cfqq(cfqd, cfqq, "alloced");
|
|
} else
|
|
cfqq = &cfqd->oom_cfqq;
|
|
}
|
|
|
|
if (new_cfqq)
|
|
kmem_cache_free(cfq_pool, new_cfqq);
|
|
|
|
return cfqq;
|
|
}
|
|
|
|
static struct cfq_queue **
|
|
cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
|
|
{
|
|
switch (ioprio_class) {
|
|
case IOPRIO_CLASS_RT:
|
|
return &cfqd->async_cfqq[0][ioprio];
|
|
case IOPRIO_CLASS_BE:
|
|
return &cfqd->async_cfqq[1][ioprio];
|
|
case IOPRIO_CLASS_IDLE:
|
|
return &cfqd->async_idle_cfqq;
|
|
default:
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
|
|
gfp_t gfp_mask)
|
|
{
|
|
const int ioprio = task_ioprio(ioc);
|
|
const int ioprio_class = task_ioprio_class(ioc);
|
|
struct cfq_queue **async_cfqq = NULL;
|
|
struct cfq_queue *cfqq = NULL;
|
|
|
|
if (!is_sync) {
|
|
async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
|
|
cfqq = *async_cfqq;
|
|
}
|
|
|
|
if (!cfqq)
|
|
cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
|
|
|
|
/*
|
|
* pin the queue now that it's allocated, scheduler exit will prune it
|
|
*/
|
|
if (!is_sync && !(*async_cfqq)) {
|
|
atomic_inc(&cfqq->ref);
|
|
*async_cfqq = cfqq;
|
|
}
|
|
|
|
atomic_inc(&cfqq->ref);
|
|
return cfqq;
|
|
}
|
|
|
|
/*
|
|
* We drop cfq io contexts lazily, so we may find a dead one.
|
|
*/
|
|
static void
|
|
cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
unsigned long flags;
|
|
|
|
WARN_ON(!list_empty(&cic->queue_list));
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
|
|
BUG_ON(ioc->ioc_data == cic);
|
|
|
|
radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
|
|
hlist_del_rcu(&cic->cic_list);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
cfq_cic_free(cic);
|
|
}
|
|
|
|
static struct cfq_io_context *
|
|
cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
unsigned long flags;
|
|
void *k;
|
|
|
|
if (unlikely(!ioc))
|
|
return NULL;
|
|
|
|
rcu_read_lock();
|
|
|
|
/*
|
|
* we maintain a last-hit cache, to avoid browsing over the tree
|
|
*/
|
|
cic = rcu_dereference(ioc->ioc_data);
|
|
if (cic && cic->key == cfqd) {
|
|
rcu_read_unlock();
|
|
return cic;
|
|
}
|
|
|
|
do {
|
|
cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
|
|
rcu_read_unlock();
|
|
if (!cic)
|
|
break;
|
|
/* ->key must be copied to avoid race with cfq_exit_queue() */
|
|
k = cic->key;
|
|
if (unlikely(!k)) {
|
|
cfq_drop_dead_cic(cfqd, ioc, cic);
|
|
rcu_read_lock();
|
|
continue;
|
|
}
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
rcu_assign_pointer(ioc->ioc_data, cic);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
break;
|
|
} while (1);
|
|
|
|
return cic;
|
|
}
|
|
|
|
/*
|
|
* Add cic into ioc, using cfqd as the search key. This enables us to lookup
|
|
* the process specific cfq io context when entered from the block layer.
|
|
* Also adds the cic to a per-cfqd list, used when this queue is removed.
|
|
*/
|
|
static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
|
|
struct cfq_io_context *cic, gfp_t gfp_mask)
|
|
{
|
|
unsigned long flags;
|
|
int ret;
|
|
|
|
ret = radix_tree_preload(gfp_mask);
|
|
if (!ret) {
|
|
cic->ioc = ioc;
|
|
cic->key = cfqd;
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
ret = radix_tree_insert(&ioc->radix_root,
|
|
(unsigned long) cfqd, cic);
|
|
if (!ret)
|
|
hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
radix_tree_preload_end();
|
|
|
|
if (!ret) {
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
list_add(&cic->queue_list, &cfqd->cic_list);
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
}
|
|
|
|
if (ret)
|
|
printk(KERN_ERR "cfq: cic link failed!\n");
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Setup general io context and cfq io context. There can be several cfq
|
|
* io contexts per general io context, if this process is doing io to more
|
|
* than one device managed by cfq.
|
|
*/
|
|
static struct cfq_io_context *
|
|
cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
|
|
{
|
|
struct io_context *ioc = NULL;
|
|
struct cfq_io_context *cic;
|
|
|
|
might_sleep_if(gfp_mask & __GFP_WAIT);
|
|
|
|
ioc = get_io_context(gfp_mask, cfqd->queue->node);
|
|
if (!ioc)
|
|
return NULL;
|
|
|
|
cic = cfq_cic_lookup(cfqd, ioc);
|
|
if (cic)
|
|
goto out;
|
|
|
|
cic = cfq_alloc_io_context(cfqd, gfp_mask);
|
|
if (cic == NULL)
|
|
goto err;
|
|
|
|
if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
|
|
goto err_free;
|
|
|
|
out:
|
|
smp_read_barrier_depends();
|
|
if (unlikely(ioc->ioprio_changed))
|
|
cfq_ioc_set_ioprio(ioc);
|
|
|
|
#ifdef CONFIG_CFQ_GROUP_IOSCHED
|
|
if (unlikely(ioc->cgroup_changed))
|
|
cfq_ioc_set_cgroup(ioc);
|
|
#endif
|
|
return cic;
|
|
err_free:
|
|
cfq_cic_free(cic);
|
|
err:
|
|
put_io_context(ioc);
|
|
return NULL;
|
|
}
|
|
|
|
static void
|
|
cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
|
|
{
|
|
unsigned long elapsed = jiffies - cic->last_end_request;
|
|
unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
|
|
|
|
cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
|
|
cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
|
|
cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
|
|
}
|
|
|
|
static void
|
|
cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct request *rq)
|
|
{
|
|
sector_t sdist = 0;
|
|
sector_t n_sec = blk_rq_sectors(rq);
|
|
if (cfqq->last_request_pos) {
|
|
if (cfqq->last_request_pos < blk_rq_pos(rq))
|
|
sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
|
|
else
|
|
sdist = cfqq->last_request_pos - blk_rq_pos(rq);
|
|
}
|
|
|
|
cfqq->seek_history <<= 1;
|
|
if (blk_queue_nonrot(cfqd->queue))
|
|
cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
|
|
else
|
|
cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
|
|
}
|
|
|
|
/*
|
|
* Disable idle window if the process thinks too long or seeks so much that
|
|
* it doesn't matter
|
|
*/
|
|
static void
|
|
cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
int old_idle, enable_idle;
|
|
|
|
/*
|
|
* Don't idle for async or idle io prio class
|
|
*/
|
|
if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
|
|
return;
|
|
|
|
enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
|
|
|
|
if (cfqq->queued[0] + cfqq->queued[1] >= 4)
|
|
cfq_mark_cfqq_deep(cfqq);
|
|
|
|
if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
|
|
(!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
|
|
enable_idle = 0;
|
|
else if (sample_valid(cic->ttime_samples)) {
|
|
if (cic->ttime_mean > cfqd->cfq_slice_idle)
|
|
enable_idle = 0;
|
|
else
|
|
enable_idle = 1;
|
|
}
|
|
|
|
if (old_idle != enable_idle) {
|
|
cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
|
|
if (enable_idle)
|
|
cfq_mark_cfqq_idle_window(cfqq);
|
|
else
|
|
cfq_clear_cfqq_idle_window(cfqq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Check if new_cfqq should preempt the currently active queue. Return 0 for
|
|
* no or if we aren't sure, a 1 will cause a preempt.
|
|
*/
|
|
static bool
|
|
cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
|
|
struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (!cfqq)
|
|
return false;
|
|
|
|
if (cfq_class_idle(new_cfqq))
|
|
return false;
|
|
|
|
if (cfq_class_idle(cfqq))
|
|
return true;
|
|
|
|
/*
|
|
* Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
|
|
*/
|
|
if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
|
|
return false;
|
|
|
|
/*
|
|
* if the new request is sync, but the currently running queue is
|
|
* not, let the sync request have priority.
|
|
*/
|
|
if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
|
|
return true;
|
|
|
|
if (new_cfqq->cfqg != cfqq->cfqg)
|
|
return false;
|
|
|
|
if (cfq_slice_used(cfqq))
|
|
return true;
|
|
|
|
/* Allow preemption only if we are idling on sync-noidle tree */
|
|
if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
|
|
cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
|
|
new_cfqq->service_tree->count == 2 &&
|
|
RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
return true;
|
|
|
|
/*
|
|
* So both queues are sync. Let the new request get disk time if
|
|
* it's a metadata request and the current queue is doing regular IO.
|
|
*/
|
|
if (rq_is_meta(rq) && !cfqq->meta_pending)
|
|
return true;
|
|
|
|
/*
|
|
* Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
|
|
*/
|
|
if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
|
|
return true;
|
|
|
|
if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
|
|
return false;
|
|
|
|
/*
|
|
* if this request is as-good as one we would expect from the
|
|
* current cfqq, let it preempt
|
|
*/
|
|
if (cfq_rq_close(cfqd, cfqq, rq))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* cfqq preempts the active queue. if we allowed preempt with no slice left,
|
|
* let it have half of its nominal slice.
|
|
*/
|
|
static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "preempt");
|
|
cfq_slice_expired(cfqd, 1);
|
|
|
|
/*
|
|
* Put the new queue at the front of the of the current list,
|
|
* so we know that it will be selected next.
|
|
*/
|
|
BUG_ON(!cfq_cfqq_on_rr(cfqq));
|
|
|
|
cfq_service_tree_add(cfqd, cfqq, 1);
|
|
|
|
cfqq->slice_end = 0;
|
|
cfq_mark_cfqq_slice_new(cfqq);
|
|
}
|
|
|
|
/*
|
|
* Called when a new fs request (rq) is added (to cfqq). Check if there's
|
|
* something we should do about it
|
|
*/
|
|
static void
|
|
cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct request *rq)
|
|
{
|
|
struct cfq_io_context *cic = RQ_CIC(rq);
|
|
|
|
cfqd->rq_queued++;
|
|
if (rq_is_meta(rq))
|
|
cfqq->meta_pending++;
|
|
|
|
cfq_update_io_thinktime(cfqd, cic);
|
|
cfq_update_io_seektime(cfqd, cfqq, rq);
|
|
cfq_update_idle_window(cfqd, cfqq, cic);
|
|
|
|
cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
|
|
|
|
if (cfqq == cfqd->active_queue) {
|
|
/*
|
|
* Remember that we saw a request from this process, but
|
|
* don't start queuing just yet. Otherwise we risk seeing lots
|
|
* of tiny requests, because we disrupt the normal plugging
|
|
* and merging. If the request is already larger than a single
|
|
* page, let it rip immediately. For that case we assume that
|
|
* merging is already done. Ditto for a busy system that
|
|
* has other work pending, don't risk delaying until the
|
|
* idle timer unplug to continue working.
|
|
*/
|
|
if (cfq_cfqq_wait_request(cfqq)) {
|
|
if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
|
|
cfqd->busy_queues > 1) {
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
cfq_clear_cfqq_wait_request(cfqq);
|
|
__blk_run_queue(cfqd->queue);
|
|
} else
|
|
cfq_mark_cfqq_must_dispatch(cfqq);
|
|
}
|
|
} else if (cfq_should_preempt(cfqd, cfqq, rq)) {
|
|
/*
|
|
* not the active queue - expire current slice if it is
|
|
* idle and has expired it's mean thinktime or this new queue
|
|
* has some old slice time left and is of higher priority or
|
|
* this new queue is RT and the current one is BE
|
|
*/
|
|
cfq_preempt_queue(cfqd, cfqq);
|
|
__blk_run_queue(cfqd->queue);
|
|
}
|
|
}
|
|
|
|
static void cfq_insert_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "insert_request");
|
|
cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
|
|
|
|
rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
|
|
list_add_tail(&rq->queuelist, &cfqq->fifo);
|
|
cfq_add_rq_rb(rq);
|
|
|
|
cfq_rq_enqueued(cfqd, cfqq, rq);
|
|
}
|
|
|
|
/*
|
|
* Update hw_tag based on peak queue depth over 50 samples under
|
|
* sufficient load.
|
|
*/
|
|
static void cfq_update_hw_tag(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq = cfqd->active_queue;
|
|
|
|
if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
|
|
cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
|
|
|
|
if (cfqd->hw_tag == 1)
|
|
return;
|
|
|
|
if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
|
|
cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
|
|
return;
|
|
|
|
/*
|
|
* If active queue hasn't enough requests and can idle, cfq might not
|
|
* dispatch sufficient requests to hardware. Don't zero hw_tag in this
|
|
* case
|
|
*/
|
|
if (cfqq && cfq_cfqq_idle_window(cfqq) &&
|
|
cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
|
|
CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
|
|
return;
|
|
|
|
if (cfqd->hw_tag_samples++ < 50)
|
|
return;
|
|
|
|
if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
|
|
cfqd->hw_tag = 1;
|
|
else
|
|
cfqd->hw_tag = 0;
|
|
}
|
|
|
|
static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_io_context *cic = cfqd->active_cic;
|
|
|
|
/* If there are other queues in the group, don't wait */
|
|
if (cfqq->cfqg->nr_cfqq > 1)
|
|
return false;
|
|
|
|
if (cfq_slice_used(cfqq))
|
|
return true;
|
|
|
|
/* if slice left is less than think time, wait busy */
|
|
if (cic && sample_valid(cic->ttime_samples)
|
|
&& (cfqq->slice_end - jiffies < cic->ttime_mean))
|
|
return true;
|
|
|
|
/*
|
|
* If think times is less than a jiffy than ttime_mean=0 and above
|
|
* will not be true. It might happen that slice has not expired yet
|
|
* but will expire soon (4-5 ns) during select_queue(). To cover the
|
|
* case where think time is less than a jiffy, mark the queue wait
|
|
* busy if only 1 jiffy is left in the slice.
|
|
*/
|
|
if (cfqq->slice_end - jiffies == 1)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static void cfq_completed_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
const int sync = rq_is_sync(rq);
|
|
unsigned long now;
|
|
|
|
now = jiffies;
|
|
cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", !!rq_noidle(rq));
|
|
|
|
cfq_update_hw_tag(cfqd);
|
|
|
|
WARN_ON(!cfqd->rq_in_driver);
|
|
WARN_ON(!cfqq->dispatched);
|
|
cfqd->rq_in_driver--;
|
|
cfqq->dispatched--;
|
|
|
|
cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
|
|
|
|
if (sync) {
|
|
RQ_CIC(rq)->last_end_request = now;
|
|
if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
|
|
cfqd->last_delayed_sync = now;
|
|
}
|
|
|
|
/*
|
|
* If this is the active queue, check if it needs to be expired,
|
|
* or if we want to idle in case it has no pending requests.
|
|
*/
|
|
if (cfqd->active_queue == cfqq) {
|
|
const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
|
|
|
|
if (cfq_cfqq_slice_new(cfqq)) {
|
|
cfq_set_prio_slice(cfqd, cfqq);
|
|
cfq_clear_cfqq_slice_new(cfqq);
|
|
}
|
|
|
|
/*
|
|
* Should we wait for next request to come in before we expire
|
|
* the queue.
|
|
*/
|
|
if (cfq_should_wait_busy(cfqd, cfqq)) {
|
|
cfqq->slice_end = jiffies + cfqd->cfq_slice_idle;
|
|
cfq_mark_cfqq_wait_busy(cfqq);
|
|
cfq_log_cfqq(cfqd, cfqq, "will busy wait");
|
|
}
|
|
|
|
/*
|
|
* Idling is not enabled on:
|
|
* - expired queues
|
|
* - idle-priority queues
|
|
* - async queues
|
|
* - queues with still some requests queued
|
|
* - when there is a close cooperator
|
|
*/
|
|
if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
|
|
cfq_slice_expired(cfqd, 1);
|
|
else if (sync && cfqq_empty &&
|
|
!cfq_close_cooperator(cfqd, cfqq)) {
|
|
cfqd->noidle_tree_requires_idle |= !rq_noidle(rq);
|
|
/*
|
|
* Idling is enabled for SYNC_WORKLOAD.
|
|
* SYNC_NOIDLE_WORKLOAD idles at the end of the tree
|
|
* only if we processed at least one !rq_noidle request
|
|
*/
|
|
if (cfqd->serving_type == SYNC_WORKLOAD
|
|
|| cfqd->noidle_tree_requires_idle
|
|
|| cfqq->cfqg->nr_cfqq == 1)
|
|
cfq_arm_slice_timer(cfqd);
|
|
}
|
|
}
|
|
|
|
if (!cfqd->rq_in_driver)
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
/*
|
|
* we temporarily boost lower priority queues if they are holding fs exclusive
|
|
* resources. they are boosted to normal prio (CLASS_BE/4)
|
|
*/
|
|
static void cfq_prio_boost(struct cfq_queue *cfqq)
|
|
{
|
|
if (has_fs_excl()) {
|
|
/*
|
|
* boost idle prio on transactions that would lock out other
|
|
* users of the filesystem
|
|
*/
|
|
if (cfq_class_idle(cfqq))
|
|
cfqq->ioprio_class = IOPRIO_CLASS_BE;
|
|
if (cfqq->ioprio > IOPRIO_NORM)
|
|
cfqq->ioprio = IOPRIO_NORM;
|
|
} else {
|
|
/*
|
|
* unboost the queue (if needed)
|
|
*/
|
|
cfqq->ioprio_class = cfqq->org_ioprio_class;
|
|
cfqq->ioprio = cfqq->org_ioprio;
|
|
}
|
|
}
|
|
|
|
static inline int __cfq_may_queue(struct cfq_queue *cfqq)
|
|
{
|
|
if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
|
|
cfq_mark_cfqq_must_alloc_slice(cfqq);
|
|
return ELV_MQUEUE_MUST;
|
|
}
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
static int cfq_may_queue(struct request_queue *q, int rw)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct task_struct *tsk = current;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_queue *cfqq;
|
|
|
|
/*
|
|
* don't force setup of a queue from here, as a call to may_queue
|
|
* does not necessarily imply that a request actually will be queued.
|
|
* so just lookup a possibly existing queue, or return 'may queue'
|
|
* if that fails
|
|
*/
|
|
cic = cfq_cic_lookup(cfqd, tsk->io_context);
|
|
if (!cic)
|
|
return ELV_MQUEUE_MAY;
|
|
|
|
cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
|
|
if (cfqq) {
|
|
cfq_init_prio_data(cfqq, cic->ioc);
|
|
cfq_prio_boost(cfqq);
|
|
|
|
return __cfq_may_queue(cfqq);
|
|
}
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
/*
|
|
* queue lock held here
|
|
*/
|
|
static void cfq_put_request(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
if (cfqq) {
|
|
const int rw = rq_data_dir(rq);
|
|
|
|
BUG_ON(!cfqq->allocated[rw]);
|
|
cfqq->allocated[rw]--;
|
|
|
|
put_io_context(RQ_CIC(rq)->ioc);
|
|
|
|
rq->elevator_private = NULL;
|
|
rq->elevator_private2 = NULL;
|
|
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
|
|
cic_set_cfqq(cic, cfqq->new_cfqq, 1);
|
|
cfq_mark_cfqq_coop(cfqq->new_cfqq);
|
|
cfq_put_queue(cfqq);
|
|
return cic_to_cfqq(cic, 1);
|
|
}
|
|
|
|
/*
|
|
* Returns NULL if a new cfqq should be allocated, or the old cfqq if this
|
|
* was the last process referring to said cfqq.
|
|
*/
|
|
static struct cfq_queue *
|
|
split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
|
|
{
|
|
if (cfqq_process_refs(cfqq) == 1) {
|
|
cfqq->pid = current->pid;
|
|
cfq_clear_cfqq_coop(cfqq);
|
|
cfq_clear_cfqq_split_coop(cfqq);
|
|
return cfqq;
|
|
}
|
|
|
|
cic_set_cfqq(cic, NULL, 1);
|
|
cfq_put_queue(cfqq);
|
|
return NULL;
|
|
}
|
|
/*
|
|
* Allocate cfq data structures associated with this request.
|
|
*/
|
|
static int
|
|
cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_io_context *cic;
|
|
const int rw = rq_data_dir(rq);
|
|
const bool is_sync = rq_is_sync(rq);
|
|
struct cfq_queue *cfqq;
|
|
unsigned long flags;
|
|
|
|
might_sleep_if(gfp_mask & __GFP_WAIT);
|
|
|
|
cic = cfq_get_io_context(cfqd, gfp_mask);
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
if (!cic)
|
|
goto queue_fail;
|
|
|
|
new_queue:
|
|
cfqq = cic_to_cfqq(cic, is_sync);
|
|
if (!cfqq || cfqq == &cfqd->oom_cfqq) {
|
|
cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
|
|
cic_set_cfqq(cic, cfqq, is_sync);
|
|
} else {
|
|
/*
|
|
* If the queue was seeky for too long, break it apart.
|
|
*/
|
|
if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
|
|
cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
|
|
cfqq = split_cfqq(cic, cfqq);
|
|
if (!cfqq)
|
|
goto new_queue;
|
|
}
|
|
|
|
/*
|
|
* Check to see if this queue is scheduled to merge with
|
|
* another, closely cooperating queue. The merging of
|
|
* queues happens here as it must be done in process context.
|
|
* The reference on new_cfqq was taken in merge_cfqqs.
|
|
*/
|
|
if (cfqq->new_cfqq)
|
|
cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
|
|
}
|
|
|
|
cfqq->allocated[rw]++;
|
|
atomic_inc(&cfqq->ref);
|
|
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
|
|
rq->elevator_private = cic;
|
|
rq->elevator_private2 = cfqq;
|
|
return 0;
|
|
|
|
queue_fail:
|
|
if (cic)
|
|
put_io_context(cic->ioc);
|
|
|
|
cfq_schedule_dispatch(cfqd);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
cfq_log(cfqd, "set_request fail");
|
|
return 1;
|
|
}
|
|
|
|
static void cfq_kick_queue(struct work_struct *work)
|
|
{
|
|
struct cfq_data *cfqd =
|
|
container_of(work, struct cfq_data, unplug_work);
|
|
struct request_queue *q = cfqd->queue;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
__blk_run_queue(cfqd->queue);
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
|
|
/*
|
|
* Timer running if the active_queue is currently idling inside its time slice
|
|
*/
|
|
static void cfq_idle_slice_timer(unsigned long data)
|
|
{
|
|
struct cfq_data *cfqd = (struct cfq_data *) data;
|
|
struct cfq_queue *cfqq;
|
|
unsigned long flags;
|
|
int timed_out = 1;
|
|
|
|
cfq_log(cfqd, "idle timer fired");
|
|
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (cfqq) {
|
|
timed_out = 0;
|
|
|
|
/*
|
|
* We saw a request before the queue expired, let it through
|
|
*/
|
|
if (cfq_cfqq_must_dispatch(cfqq))
|
|
goto out_kick;
|
|
|
|
/*
|
|
* expired
|
|
*/
|
|
if (cfq_slice_used(cfqq))
|
|
goto expire;
|
|
|
|
/*
|
|
* only expire and reinvoke request handler, if there are
|
|
* other queues with pending requests
|
|
*/
|
|
if (!cfqd->busy_queues)
|
|
goto out_cont;
|
|
|
|
/*
|
|
* not expired and it has a request pending, let it dispatch
|
|
*/
|
|
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
goto out_kick;
|
|
|
|
/*
|
|
* Queue depth flag is reset only when the idle didn't succeed
|
|
*/
|
|
cfq_clear_cfqq_deep(cfqq);
|
|
}
|
|
expire:
|
|
cfq_slice_expired(cfqd, timed_out);
|
|
out_kick:
|
|
cfq_schedule_dispatch(cfqd);
|
|
out_cont:
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
|
|
static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
|
|
{
|
|
del_timer_sync(&cfqd->idle_slice_timer);
|
|
cancel_work_sync(&cfqd->unplug_work);
|
|
}
|
|
|
|
static void cfq_put_async_queues(struct cfq_data *cfqd)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < IOPRIO_BE_NR; i++) {
|
|
if (cfqd->async_cfqq[0][i])
|
|
cfq_put_queue(cfqd->async_cfqq[0][i]);
|
|
if (cfqd->async_cfqq[1][i])
|
|
cfq_put_queue(cfqd->async_cfqq[1][i]);
|
|
}
|
|
|
|
if (cfqd->async_idle_cfqq)
|
|
cfq_put_queue(cfqd->async_idle_cfqq);
|
|
}
|
|
|
|
static void cfq_cfqd_free(struct rcu_head *head)
|
|
{
|
|
kfree(container_of(head, struct cfq_data, rcu));
|
|
}
|
|
|
|
static void cfq_exit_queue(struct elevator_queue *e)
|
|
{
|
|
struct cfq_data *cfqd = e->elevator_data;
|
|
struct request_queue *q = cfqd->queue;
|
|
|
|
cfq_shutdown_timer_wq(cfqd);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
if (cfqd->active_queue)
|
|
__cfq_slice_expired(cfqd, cfqd->active_queue, 0);
|
|
|
|
while (!list_empty(&cfqd->cic_list)) {
|
|
struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
|
|
struct cfq_io_context,
|
|
queue_list);
|
|
|
|
__cfq_exit_single_io_context(cfqd, cic);
|
|
}
|
|
|
|
cfq_put_async_queues(cfqd);
|
|
cfq_release_cfq_groups(cfqd);
|
|
blkiocg_del_blkio_group(&cfqd->root_group.blkg);
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
cfq_shutdown_timer_wq(cfqd);
|
|
|
|
/* Wait for cfqg->blkg->key accessors to exit their grace periods. */
|
|
call_rcu(&cfqd->rcu, cfq_cfqd_free);
|
|
}
|
|
|
|
static void *cfq_init_queue(struct request_queue *q)
|
|
{
|
|
struct cfq_data *cfqd;
|
|
int i, j;
|
|
struct cfq_group *cfqg;
|
|
struct cfq_rb_root *st;
|
|
|
|
cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
|
|
if (!cfqd)
|
|
return NULL;
|
|
|
|
/* Init root service tree */
|
|
cfqd->grp_service_tree = CFQ_RB_ROOT;
|
|
|
|
/* Init root group */
|
|
cfqg = &cfqd->root_group;
|
|
for_each_cfqg_st(cfqg, i, j, st)
|
|
*st = CFQ_RB_ROOT;
|
|
RB_CLEAR_NODE(&cfqg->rb_node);
|
|
|
|
/* Give preference to root group over other groups */
|
|
cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
|
|
|
|
#ifdef CONFIG_CFQ_GROUP_IOSCHED
|
|
/*
|
|
* Take a reference to root group which we never drop. This is just
|
|
* to make sure that cfq_put_cfqg() does not try to kfree root group
|
|
*/
|
|
atomic_set(&cfqg->ref, 1);
|
|
rcu_read_lock();
|
|
blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd,
|
|
0);
|
|
rcu_read_unlock();
|
|
#endif
|
|
/*
|
|
* Not strictly needed (since RB_ROOT just clears the node and we
|
|
* zeroed cfqd on alloc), but better be safe in case someone decides
|
|
* to add magic to the rb code
|
|
*/
|
|
for (i = 0; i < CFQ_PRIO_LISTS; i++)
|
|
cfqd->prio_trees[i] = RB_ROOT;
|
|
|
|
/*
|
|
* Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
|
|
* Grab a permanent reference to it, so that the normal code flow
|
|
* will not attempt to free it.
|
|
*/
|
|
cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
|
|
atomic_inc(&cfqd->oom_cfqq.ref);
|
|
cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
|
|
|
|
INIT_LIST_HEAD(&cfqd->cic_list);
|
|
|
|
cfqd->queue = q;
|
|
|
|
init_timer(&cfqd->idle_slice_timer);
|
|
cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
|
|
cfqd->idle_slice_timer.data = (unsigned long) cfqd;
|
|
|
|
INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
|
|
|
|
cfqd->cfq_quantum = cfq_quantum;
|
|
cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
|
|
cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
|
|
cfqd->cfq_back_max = cfq_back_max;
|
|
cfqd->cfq_back_penalty = cfq_back_penalty;
|
|
cfqd->cfq_slice[0] = cfq_slice_async;
|
|
cfqd->cfq_slice[1] = cfq_slice_sync;
|
|
cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
|
|
cfqd->cfq_slice_idle = cfq_slice_idle;
|
|
cfqd->cfq_latency = 1;
|
|
cfqd->cfq_group_isolation = 0;
|
|
cfqd->hw_tag = -1;
|
|
/*
|
|
* we optimistically start assuming sync ops weren't delayed in last
|
|
* second, in order to have larger depth for async operations.
|
|
*/
|
|
cfqd->last_delayed_sync = jiffies - HZ;
|
|
INIT_RCU_HEAD(&cfqd->rcu);
|
|
return cfqd;
|
|
}
|
|
|
|
static void cfq_slab_kill(void)
|
|
{
|
|
/*
|
|
* Caller already ensured that pending RCU callbacks are completed,
|
|
* so we should have no busy allocations at this point.
|
|
*/
|
|
if (cfq_pool)
|
|
kmem_cache_destroy(cfq_pool);
|
|
if (cfq_ioc_pool)
|
|
kmem_cache_destroy(cfq_ioc_pool);
|
|
}
|
|
|
|
static int __init cfq_slab_setup(void)
|
|
{
|
|
cfq_pool = KMEM_CACHE(cfq_queue, 0);
|
|
if (!cfq_pool)
|
|
goto fail;
|
|
|
|
cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
|
|
if (!cfq_ioc_pool)
|
|
goto fail;
|
|
|
|
return 0;
|
|
fail:
|
|
cfq_slab_kill();
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* sysfs parts below -->
|
|
*/
|
|
static ssize_t
|
|
cfq_var_show(unsigned int var, char *page)
|
|
{
|
|
return sprintf(page, "%d\n", var);
|
|
}
|
|
|
|
static ssize_t
|
|
cfq_var_store(unsigned int *var, const char *page, size_t count)
|
|
{
|
|
char *p = (char *) page;
|
|
|
|
*var = simple_strtoul(p, &p, 10);
|
|
return count;
|
|
}
|
|
|
|
#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
|
|
static ssize_t __FUNC(struct elevator_queue *e, char *page) \
|
|
{ \
|
|
struct cfq_data *cfqd = e->elevator_data; \
|
|
unsigned int __data = __VAR; \
|
|
if (__CONV) \
|
|
__data = jiffies_to_msecs(__data); \
|
|
return cfq_var_show(__data, (page)); \
|
|
}
|
|
SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
|
|
SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
|
|
SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
|
|
SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
|
|
SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
|
|
SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
|
|
SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
|
|
SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
|
|
SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
|
|
SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
|
|
SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0);
|
|
#undef SHOW_FUNCTION
|
|
|
|
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
|
|
static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
|
|
{ \
|
|
struct cfq_data *cfqd = e->elevator_data; \
|
|
unsigned int __data; \
|
|
int ret = cfq_var_store(&__data, (page), count); \
|
|
if (__data < (MIN)) \
|
|
__data = (MIN); \
|
|
else if (__data > (MAX)) \
|
|
__data = (MAX); \
|
|
if (__CONV) \
|
|
*(__PTR) = msecs_to_jiffies(__data); \
|
|
else \
|
|
*(__PTR) = __data; \
|
|
return ret; \
|
|
}
|
|
STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
|
|
STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
|
|
UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
|
|
UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
|
|
STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
|
|
UINT_MAX, 0);
|
|
STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
|
|
UINT_MAX, 0);
|
|
STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
|
|
STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0);
|
|
#undef STORE_FUNCTION
|
|
|
|
#define CFQ_ATTR(name) \
|
|
__ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
|
|
|
|
static struct elv_fs_entry cfq_attrs[] = {
|
|
CFQ_ATTR(quantum),
|
|
CFQ_ATTR(fifo_expire_sync),
|
|
CFQ_ATTR(fifo_expire_async),
|
|
CFQ_ATTR(back_seek_max),
|
|
CFQ_ATTR(back_seek_penalty),
|
|
CFQ_ATTR(slice_sync),
|
|
CFQ_ATTR(slice_async),
|
|
CFQ_ATTR(slice_async_rq),
|
|
CFQ_ATTR(slice_idle),
|
|
CFQ_ATTR(low_latency),
|
|
CFQ_ATTR(group_isolation),
|
|
__ATTR_NULL
|
|
};
|
|
|
|
static struct elevator_type iosched_cfq = {
|
|
.ops = {
|
|
.elevator_merge_fn = cfq_merge,
|
|
.elevator_merged_fn = cfq_merged_request,
|
|
.elevator_merge_req_fn = cfq_merged_requests,
|
|
.elevator_allow_merge_fn = cfq_allow_merge,
|
|
.elevator_dispatch_fn = cfq_dispatch_requests,
|
|
.elevator_add_req_fn = cfq_insert_request,
|
|
.elevator_activate_req_fn = cfq_activate_request,
|
|
.elevator_deactivate_req_fn = cfq_deactivate_request,
|
|
.elevator_queue_empty_fn = cfq_queue_empty,
|
|
.elevator_completed_req_fn = cfq_completed_request,
|
|
.elevator_former_req_fn = elv_rb_former_request,
|
|
.elevator_latter_req_fn = elv_rb_latter_request,
|
|
.elevator_set_req_fn = cfq_set_request,
|
|
.elevator_put_req_fn = cfq_put_request,
|
|
.elevator_may_queue_fn = cfq_may_queue,
|
|
.elevator_init_fn = cfq_init_queue,
|
|
.elevator_exit_fn = cfq_exit_queue,
|
|
.trim = cfq_free_io_context,
|
|
},
|
|
.elevator_attrs = cfq_attrs,
|
|
.elevator_name = "cfq",
|
|
.elevator_owner = THIS_MODULE,
|
|
};
|
|
|
|
#ifdef CONFIG_CFQ_GROUP_IOSCHED
|
|
static struct blkio_policy_type blkio_policy_cfq = {
|
|
.ops = {
|
|
.blkio_unlink_group_fn = cfq_unlink_blkio_group,
|
|
.blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
|
|
},
|
|
};
|
|
#else
|
|
static struct blkio_policy_type blkio_policy_cfq;
|
|
#endif
|
|
|
|
static int __init cfq_init(void)
|
|
{
|
|
/*
|
|
* could be 0 on HZ < 1000 setups
|
|
*/
|
|
if (!cfq_slice_async)
|
|
cfq_slice_async = 1;
|
|
if (!cfq_slice_idle)
|
|
cfq_slice_idle = 1;
|
|
|
|
if (cfq_slab_setup())
|
|
return -ENOMEM;
|
|
|
|
elv_register(&iosched_cfq);
|
|
blkio_policy_register(&blkio_policy_cfq);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __exit cfq_exit(void)
|
|
{
|
|
DECLARE_COMPLETION_ONSTACK(all_gone);
|
|
blkio_policy_unregister(&blkio_policy_cfq);
|
|
elv_unregister(&iosched_cfq);
|
|
ioc_gone = &all_gone;
|
|
/* ioc_gone's update must be visible before reading ioc_count */
|
|
smp_wmb();
|
|
|
|
/*
|
|
* this also protects us from entering cfq_slab_kill() with
|
|
* pending RCU callbacks
|
|
*/
|
|
if (elv_ioc_count_read(cfq_ioc_count))
|
|
wait_for_completion(&all_gone);
|
|
cfq_slab_kill();
|
|
}
|
|
|
|
module_init(cfq_init);
|
|
module_exit(cfq_exit);
|
|
|
|
MODULE_AUTHOR("Jens Axboe");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
|