165 lines
5.6 KiB
C
165 lines
5.6 KiB
C
#ifndef __NET_SCHED_CODEL_H
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#define __NET_SCHED_CODEL_H
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/*
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* Codel - The Controlled-Delay Active Queue Management algorithm
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*
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* Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com>
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* Copyright (C) 2011-2012 Van Jacobson <van@pollere.net>
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* Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net>
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* Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions, and the following disclaimer,
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* without modification.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The names of the authors may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* Alternatively, provided that this notice is retained in full, this
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* software may be distributed under the terms of the GNU General
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* Public License ("GPL") version 2, in which case the provisions of the
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* GPL apply INSTEAD OF those given above.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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*/
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#include <linux/types.h>
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#include <linux/ktime.h>
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#include <linux/skbuff.h>
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#include <net/pkt_sched.h>
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#include <net/inet_ecn.h>
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/* Controlling Queue Delay (CoDel) algorithm
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* =========================================
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* Source : Kathleen Nichols and Van Jacobson
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* http://queue.acm.org/detail.cfm?id=2209336
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*
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* Implemented on linux by Dave Taht and Eric Dumazet
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*/
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/* CoDel uses a 1024 nsec clock, encoded in u32
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* This gives a range of 2199 seconds, because of signed compares
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*/
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typedef u32 codel_time_t;
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typedef s32 codel_tdiff_t;
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#define CODEL_SHIFT 10
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#define MS2TIME(a) ((a * NSEC_PER_MSEC) >> CODEL_SHIFT)
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static inline codel_time_t codel_get_time(void)
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{
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u64 ns = ktime_get_ns();
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return ns >> CODEL_SHIFT;
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}
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/* Dealing with timer wrapping, according to RFC 1982, as desc in wikipedia:
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* https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
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* codel_time_after(a,b) returns true if the time a is after time b.
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*/
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#define codel_time_after(a, b) \
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(typecheck(codel_time_t, a) && \
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typecheck(codel_time_t, b) && \
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((s32)((a) - (b)) > 0))
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#define codel_time_before(a, b) codel_time_after(b, a)
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#define codel_time_after_eq(a, b) \
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(typecheck(codel_time_t, a) && \
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typecheck(codel_time_t, b) && \
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((s32)((a) - (b)) >= 0))
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#define codel_time_before_eq(a, b) codel_time_after_eq(b, a)
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static inline u32 codel_time_to_us(codel_time_t val)
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{
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u64 valns = ((u64)val << CODEL_SHIFT);
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do_div(valns, NSEC_PER_USEC);
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return (u32)valns;
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}
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/**
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* struct codel_params - contains codel parameters
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* @target: target queue size (in time units)
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* @ce_threshold: threshold for marking packets with ECN CE
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* @interval: width of moving time window
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* @mtu: device mtu, or minimal queue backlog in bytes.
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* @ecn: is Explicit Congestion Notification enabled
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*/
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struct codel_params {
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codel_time_t target;
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codel_time_t ce_threshold;
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codel_time_t interval;
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u32 mtu;
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bool ecn;
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};
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/**
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* struct codel_vars - contains codel variables
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* @count: how many drops we've done since the last time we
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* entered dropping state
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* @lastcount: count at entry to dropping state
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* @dropping: set to true if in dropping state
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* @rec_inv_sqrt: reciprocal value of sqrt(count) >> 1
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* @first_above_time: when we went (or will go) continuously above target
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* for interval
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* @drop_next: time to drop next packet, or when we dropped last
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* @ldelay: sojourn time of last dequeued packet
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*/
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struct codel_vars {
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u32 count;
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u32 lastcount;
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bool dropping;
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u16 rec_inv_sqrt;
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codel_time_t first_above_time;
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codel_time_t drop_next;
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codel_time_t ldelay;
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};
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#define REC_INV_SQRT_BITS (8 * sizeof(u16)) /* or sizeof_in_bits(rec_inv_sqrt) */
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/* needed shift to get a Q0.32 number from rec_inv_sqrt */
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#define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS)
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/**
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* struct codel_stats - contains codel shared variables and stats
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* @maxpacket: largest packet we've seen so far
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* @drop_count: temp count of dropped packets in dequeue()
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* @drop_len: bytes of dropped packets in dequeue()
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* ecn_mark: number of packets we ECN marked instead of dropping
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* ce_mark: number of packets CE marked because sojourn time was above ce_threshold
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*/
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struct codel_stats {
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u32 maxpacket;
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u32 drop_count;
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u32 drop_len;
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u32 ecn_mark;
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u32 ce_mark;
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};
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#define CODEL_DISABLED_THRESHOLD INT_MAX
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typedef u32 (*codel_skb_len_t)(const struct sk_buff *skb);
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typedef codel_time_t (*codel_skb_time_t)(const struct sk_buff *skb);
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typedef void (*codel_skb_drop_t)(struct sk_buff *skb, void *ctx);
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typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars,
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void *ctx);
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#endif
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