479 lines
11 KiB
C
479 lines
11 KiB
C
/*
|
|
* Tag allocation using scalable bitmaps. Uses active queue tracking to support
|
|
* fairer distribution of tags between multiple submitters when a shared tag map
|
|
* is used.
|
|
*
|
|
* Copyright (C) 2013-2014 Jens Axboe
|
|
*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
|
|
#include <linux/blk-mq.h>
|
|
#include "blk.h"
|
|
#include "blk-mq.h"
|
|
#include "blk-mq-tag.h"
|
|
|
|
bool blk_mq_has_free_tags(struct blk_mq_tags *tags)
|
|
{
|
|
if (!tags)
|
|
return true;
|
|
|
|
return sbitmap_any_bit_clear(&tags->bitmap_tags.sb);
|
|
}
|
|
|
|
/*
|
|
* If a previously inactive queue goes active, bump the active user count.
|
|
*/
|
|
bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx)
|
|
{
|
|
if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) &&
|
|
!test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
|
|
atomic_inc(&hctx->tags->active_queues);
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Wakeup all potentially sleeping on tags
|
|
*/
|
|
void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve)
|
|
{
|
|
sbitmap_queue_wake_all(&tags->bitmap_tags);
|
|
if (include_reserve)
|
|
sbitmap_queue_wake_all(&tags->breserved_tags);
|
|
}
|
|
|
|
/*
|
|
* If a previously busy queue goes inactive, potential waiters could now
|
|
* be allowed to queue. Wake them up and check.
|
|
*/
|
|
void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
|
|
{
|
|
struct blk_mq_tags *tags = hctx->tags;
|
|
|
|
if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
|
|
return;
|
|
|
|
atomic_dec(&tags->active_queues);
|
|
|
|
blk_mq_tag_wakeup_all(tags, false);
|
|
}
|
|
|
|
/*
|
|
* For shared tag users, we track the number of currently active users
|
|
* and attempt to provide a fair share of the tag depth for each of them.
|
|
*/
|
|
static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
|
|
struct sbitmap_queue *bt)
|
|
{
|
|
unsigned int depth, users;
|
|
|
|
if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_SHARED))
|
|
return true;
|
|
if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
|
|
return true;
|
|
|
|
/*
|
|
* Don't try dividing an ant
|
|
*/
|
|
if (bt->sb.depth == 1)
|
|
return true;
|
|
|
|
users = atomic_read(&hctx->tags->active_queues);
|
|
if (!users)
|
|
return true;
|
|
|
|
/*
|
|
* Allow at least some tags
|
|
*/
|
|
depth = max((bt->sb.depth + users - 1) / users, 4U);
|
|
return atomic_read(&hctx->nr_active) < depth;
|
|
}
|
|
|
|
static int __bt_get(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt)
|
|
{
|
|
if (!hctx_may_queue(hctx, bt))
|
|
return -1;
|
|
return __sbitmap_queue_get(bt);
|
|
}
|
|
|
|
static int bt_get(struct blk_mq_alloc_data *data, struct sbitmap_queue *bt,
|
|
struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags)
|
|
{
|
|
struct sbq_wait_state *ws;
|
|
DEFINE_WAIT(wait);
|
|
int tag;
|
|
|
|
tag = __bt_get(hctx, bt);
|
|
if (tag != -1)
|
|
return tag;
|
|
|
|
if (data->flags & BLK_MQ_REQ_NOWAIT)
|
|
return -1;
|
|
|
|
ws = bt_wait_ptr(bt, hctx);
|
|
do {
|
|
prepare_to_wait(&ws->wait, &wait, TASK_UNINTERRUPTIBLE);
|
|
|
|
tag = __bt_get(hctx, bt);
|
|
if (tag != -1)
|
|
break;
|
|
|
|
/*
|
|
* We're out of tags on this hardware queue, kick any
|
|
* pending IO submits before going to sleep waiting for
|
|
* some to complete. Note that hctx can be NULL here for
|
|
* reserved tag allocation.
|
|
*/
|
|
if (hctx)
|
|
blk_mq_run_hw_queue(hctx, false);
|
|
|
|
/*
|
|
* Retry tag allocation after running the hardware queue,
|
|
* as running the queue may also have found completions.
|
|
*/
|
|
tag = __bt_get(hctx, bt);
|
|
if (tag != -1)
|
|
break;
|
|
|
|
blk_mq_put_ctx(data->ctx);
|
|
|
|
io_schedule();
|
|
|
|
data->ctx = blk_mq_get_ctx(data->q);
|
|
data->hctx = blk_mq_map_queue(data->q, data->ctx->cpu);
|
|
if (data->flags & BLK_MQ_REQ_RESERVED) {
|
|
bt = &data->hctx->tags->breserved_tags;
|
|
} else {
|
|
hctx = data->hctx;
|
|
bt = &hctx->tags->bitmap_tags;
|
|
}
|
|
finish_wait(&ws->wait, &wait);
|
|
ws = bt_wait_ptr(bt, hctx);
|
|
} while (1);
|
|
|
|
finish_wait(&ws->wait, &wait);
|
|
return tag;
|
|
}
|
|
|
|
static unsigned int __blk_mq_get_tag(struct blk_mq_alloc_data *data)
|
|
{
|
|
int tag;
|
|
|
|
tag = bt_get(data, &data->hctx->tags->bitmap_tags, data->hctx,
|
|
data->hctx->tags);
|
|
if (tag >= 0)
|
|
return tag + data->hctx->tags->nr_reserved_tags;
|
|
|
|
return BLK_MQ_TAG_FAIL;
|
|
}
|
|
|
|
static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_alloc_data *data)
|
|
{
|
|
int tag;
|
|
|
|
if (unlikely(!data->hctx->tags->nr_reserved_tags)) {
|
|
WARN_ON_ONCE(1);
|
|
return BLK_MQ_TAG_FAIL;
|
|
}
|
|
|
|
tag = bt_get(data, &data->hctx->tags->breserved_tags, NULL,
|
|
data->hctx->tags);
|
|
if (tag < 0)
|
|
return BLK_MQ_TAG_FAIL;
|
|
|
|
return tag;
|
|
}
|
|
|
|
unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
|
|
{
|
|
if (data->flags & BLK_MQ_REQ_RESERVED)
|
|
return __blk_mq_get_reserved_tag(data);
|
|
return __blk_mq_get_tag(data);
|
|
}
|
|
|
|
void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
|
|
unsigned int tag)
|
|
{
|
|
struct blk_mq_tags *tags = hctx->tags;
|
|
|
|
if (tag >= tags->nr_reserved_tags) {
|
|
const int real_tag = tag - tags->nr_reserved_tags;
|
|
|
|
BUG_ON(real_tag >= tags->nr_tags);
|
|
sbitmap_queue_clear(&tags->bitmap_tags, real_tag, ctx->cpu);
|
|
} else {
|
|
BUG_ON(tag >= tags->nr_reserved_tags);
|
|
sbitmap_queue_clear(&tags->breserved_tags, tag, ctx->cpu);
|
|
}
|
|
}
|
|
|
|
struct bt_iter_data {
|
|
struct blk_mq_hw_ctx *hctx;
|
|
busy_iter_fn *fn;
|
|
void *data;
|
|
bool reserved;
|
|
};
|
|
|
|
static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
|
|
{
|
|
struct bt_iter_data *iter_data = data;
|
|
struct blk_mq_hw_ctx *hctx = iter_data->hctx;
|
|
struct blk_mq_tags *tags = hctx->tags;
|
|
bool reserved = iter_data->reserved;
|
|
struct request *rq;
|
|
|
|
if (!reserved)
|
|
bitnr += tags->nr_reserved_tags;
|
|
rq = tags->rqs[bitnr];
|
|
|
|
if (rq->q == hctx->queue)
|
|
iter_data->fn(hctx, rq, iter_data->data, reserved);
|
|
return true;
|
|
}
|
|
|
|
static void bt_for_each(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt,
|
|
busy_iter_fn *fn, void *data, bool reserved)
|
|
{
|
|
struct bt_iter_data iter_data = {
|
|
.hctx = hctx,
|
|
.fn = fn,
|
|
.data = data,
|
|
.reserved = reserved,
|
|
};
|
|
|
|
sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data);
|
|
}
|
|
|
|
struct bt_tags_iter_data {
|
|
struct blk_mq_tags *tags;
|
|
busy_tag_iter_fn *fn;
|
|
void *data;
|
|
bool reserved;
|
|
};
|
|
|
|
static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
|
|
{
|
|
struct bt_tags_iter_data *iter_data = data;
|
|
struct blk_mq_tags *tags = iter_data->tags;
|
|
bool reserved = iter_data->reserved;
|
|
struct request *rq;
|
|
|
|
if (!reserved)
|
|
bitnr += tags->nr_reserved_tags;
|
|
rq = tags->rqs[bitnr];
|
|
|
|
iter_data->fn(rq, iter_data->data, reserved);
|
|
return true;
|
|
}
|
|
|
|
static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt,
|
|
busy_tag_iter_fn *fn, void *data, bool reserved)
|
|
{
|
|
struct bt_tags_iter_data iter_data = {
|
|
.tags = tags,
|
|
.fn = fn,
|
|
.data = data,
|
|
.reserved = reserved,
|
|
};
|
|
|
|
if (tags->rqs)
|
|
sbitmap_for_each_set(&bt->sb, bt_tags_iter, &iter_data);
|
|
}
|
|
|
|
static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags,
|
|
busy_tag_iter_fn *fn, void *priv)
|
|
{
|
|
if (tags->nr_reserved_tags)
|
|
bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true);
|
|
bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false);
|
|
}
|
|
|
|
void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
|
|
busy_tag_iter_fn *fn, void *priv)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < tagset->nr_hw_queues; i++) {
|
|
if (tagset->tags && tagset->tags[i])
|
|
blk_mq_all_tag_busy_iter(tagset->tags[i], fn, priv);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(blk_mq_tagset_busy_iter);
|
|
|
|
int blk_mq_reinit_tagset(struct blk_mq_tag_set *set)
|
|
{
|
|
int i, j, ret = 0;
|
|
|
|
if (!set->ops->reinit_request)
|
|
goto out;
|
|
|
|
for (i = 0; i < set->nr_hw_queues; i++) {
|
|
struct blk_mq_tags *tags = set->tags[i];
|
|
|
|
for (j = 0; j < tags->nr_tags; j++) {
|
|
if (!tags->rqs[j])
|
|
continue;
|
|
|
|
ret = set->ops->reinit_request(set->driver_data,
|
|
tags->rqs[j]);
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_mq_reinit_tagset);
|
|
|
|
void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn,
|
|
void *priv)
|
|
{
|
|
struct blk_mq_hw_ctx *hctx;
|
|
int i;
|
|
|
|
|
|
queue_for_each_hw_ctx(q, hctx, i) {
|
|
struct blk_mq_tags *tags = hctx->tags;
|
|
|
|
/*
|
|
* If not software queues are currently mapped to this
|
|
* hardware queue, there's nothing to check
|
|
*/
|
|
if (!blk_mq_hw_queue_mapped(hctx))
|
|
continue;
|
|
|
|
if (tags->nr_reserved_tags)
|
|
bt_for_each(hctx, &tags->breserved_tags, fn, priv, true);
|
|
bt_for_each(hctx, &tags->bitmap_tags, fn, priv, false);
|
|
}
|
|
|
|
}
|
|
|
|
static unsigned int bt_unused_tags(const struct sbitmap_queue *bt)
|
|
{
|
|
return bt->sb.depth - sbitmap_weight(&bt->sb);
|
|
}
|
|
|
|
static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth,
|
|
bool round_robin, int node)
|
|
{
|
|
return sbitmap_queue_init_node(bt, depth, -1, round_robin, GFP_KERNEL,
|
|
node);
|
|
}
|
|
|
|
static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags,
|
|
int node, int alloc_policy)
|
|
{
|
|
unsigned int depth = tags->nr_tags - tags->nr_reserved_tags;
|
|
bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR;
|
|
|
|
if (bt_alloc(&tags->bitmap_tags, depth, round_robin, node))
|
|
goto free_tags;
|
|
if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, round_robin,
|
|
node))
|
|
goto free_bitmap_tags;
|
|
|
|
return tags;
|
|
free_bitmap_tags:
|
|
sbitmap_queue_free(&tags->bitmap_tags);
|
|
free_tags:
|
|
kfree(tags);
|
|
return NULL;
|
|
}
|
|
|
|
struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
|
|
unsigned int reserved_tags,
|
|
int node, int alloc_policy)
|
|
{
|
|
struct blk_mq_tags *tags;
|
|
|
|
if (total_tags > BLK_MQ_TAG_MAX) {
|
|
pr_err("blk-mq: tag depth too large\n");
|
|
return NULL;
|
|
}
|
|
|
|
tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node);
|
|
if (!tags)
|
|
return NULL;
|
|
|
|
tags->nr_tags = total_tags;
|
|
tags->nr_reserved_tags = reserved_tags;
|
|
|
|
return blk_mq_init_bitmap_tags(tags, node, alloc_policy);
|
|
}
|
|
|
|
void blk_mq_free_tags(struct blk_mq_tags *tags)
|
|
{
|
|
sbitmap_queue_free(&tags->bitmap_tags);
|
|
sbitmap_queue_free(&tags->breserved_tags);
|
|
kfree(tags);
|
|
}
|
|
|
|
int blk_mq_tag_update_depth(struct blk_mq_tags *tags, unsigned int tdepth)
|
|
{
|
|
tdepth -= tags->nr_reserved_tags;
|
|
if (tdepth > tags->nr_tags)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Don't need (or can't) update reserved tags here, they remain
|
|
* static and should never need resizing.
|
|
*/
|
|
sbitmap_queue_resize(&tags->bitmap_tags, tdepth);
|
|
|
|
blk_mq_tag_wakeup_all(tags, false);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* blk_mq_unique_tag() - return a tag that is unique queue-wide
|
|
* @rq: request for which to compute a unique tag
|
|
*
|
|
* The tag field in struct request is unique per hardware queue but not over
|
|
* all hardware queues. Hence this function that returns a tag with the
|
|
* hardware context index in the upper bits and the per hardware queue tag in
|
|
* the lower bits.
|
|
*
|
|
* Note: When called for a request that is queued on a non-multiqueue request
|
|
* queue, the hardware context index is set to zero.
|
|
*/
|
|
u32 blk_mq_unique_tag(struct request *rq)
|
|
{
|
|
struct request_queue *q = rq->q;
|
|
struct blk_mq_hw_ctx *hctx;
|
|
int hwq = 0;
|
|
|
|
if (q->mq_ops) {
|
|
hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
|
|
hwq = hctx->queue_num;
|
|
}
|
|
|
|
return (hwq << BLK_MQ_UNIQUE_TAG_BITS) |
|
|
(rq->tag & BLK_MQ_UNIQUE_TAG_MASK);
|
|
}
|
|
EXPORT_SYMBOL(blk_mq_unique_tag);
|
|
|
|
ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page)
|
|
{
|
|
char *orig_page = page;
|
|
unsigned int free, res;
|
|
|
|
if (!tags)
|
|
return 0;
|
|
|
|
page += sprintf(page, "nr_tags=%u, reserved_tags=%u, "
|
|
"bits_per_word=%u\n",
|
|
tags->nr_tags, tags->nr_reserved_tags,
|
|
1U << tags->bitmap_tags.sb.shift);
|
|
|
|
free = bt_unused_tags(&tags->bitmap_tags);
|
|
res = bt_unused_tags(&tags->breserved_tags);
|
|
|
|
page += sprintf(page, "nr_free=%u, nr_reserved=%u\n", free, res);
|
|
page += sprintf(page, "active_queues=%u\n", atomic_read(&tags->active_queues));
|
|
|
|
return page - orig_page;
|
|
}
|