#ifndef __NET_SCHED_CODEL_H#define __NET_SCHED_CODEL_H /* * Codel - The Controlled-Delay Active Queue Management algorithm * * Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com> * Copyright (C) 2011-2012 Van Jacobson <van@pollere.net> * Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net> * Copyright (C) 2012 Eric Dumazet <edumazet@google.com> * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions, and the following disclaimer, * without modification. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The names of the authors may not be used to endorse or promote products * derived from this software without specific prior written permission. * * Alternatively, provided that this notice is retained in full, this * software may be distributed under the terms of the GNU General * Public License ("GPL") version 2, in which case the provisions of the * GPL apply INSTEAD OF those given above. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH * DAMAGE. * */ #include <linux/types.h>#include <linux/ktime.h>#include <linux/skbuff.h>#include <net/pkt_sched.h>#include <net/inet_ecn.h> /* Controlling Queue Delay (CoDel) algorithm * ========================================= * Source : Kathleen Nichols and Van Jacobson * http://queue.acm.org/detail.cfm?id=2209336 * * Implemented on linux by Dave Taht and Eric Dumazet */ /* CoDel uses a 1024 nsec clock, encoded in u32 * This gives a range of 2199 seconds, because of signed compares */typedef u32 codel_time_t;typedef s32 codel_tdiff_t;#define CODEL_SHIFT 10#define MS2TIME(a) ((a * NSEC_PER_MSEC) >> CODEL_SHIFT) static inline codel_time_t codel_get_time(void){ u64 ns = ktime_get_ns(); return ns >> CODEL_SHIFT;} /* Dealing with timer wrapping, according to RFC 1982, as desc in wikipedia: * https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution * codel_time_after(a,b) returns true if the time a is after time b. */#define codel_time_after(a, b) \ (typecheck(codel_time_t, a) && \ typecheck(codel_time_t, b) && \ ((s32)((a) - (b)) > 0))#define codel_time_before(a, b) codel_time_after(b, a) #define codel_time_after_eq(a, b) \ (typecheck(codel_time_t, a) && \ typecheck(codel_time_t, b) && \ ((s32)((a) - (b)) >= 0))#define codel_time_before_eq(a, b) codel_time_after_eq(b, a) /* Qdiscs using codel plugin must use codel_skb_cb in their own cb[] */struct codel_skb_cb { codel_time_t enqueue_time;}; static struct codel_skb_cb *get_codel_cb(const struct sk_buff *skb){ qdisc_cb_private_validate(skb, sizeof(struct codel_skb_cb)); return (struct codel_skb_cb *)qdisc_skb_cb(skb)->data;} static codel_time_t codel_get_enqueue_time(const struct sk_buff *skb){ return get_codel_cb(skb)->enqueue_time;} static void codel_set_enqueue_time(struct sk_buff *skb){ get_codel_cb(skb)->enqueue_time = codel_get_time();} static inline u32 codel_time_to_us(codel_time_t val){ u64 valns = ((u64)val << CODEL_SHIFT); do_div(valns, NSEC_PER_USEC); return (u32)valns;} /** * struct codel_params - contains codel parameters * @target: target queue size (in time units) * @interval: width of moving time window * @ecn: is Explicit Congestion Notification enabled */struct codel_params { codel_time_t target; codel_time_t interval; bool ecn;}; /** * struct codel_vars - contains codel variables * @count: how many drops we've done since the last time we * entered dropping state * @lastcount: count at entry to dropping state * @dropping: set to true if in dropping state * @rec_inv_sqrt: reciprocal value of sqrt(count) >> 1 * @first_above_time: when we went (or will go) continuously above target * for interval * @drop_next: time to drop next packet, or when we dropped last * @ldelay: sojourn time of last dequeued packet */struct codel_vars { u32 count; u32 lastcount; bool dropping; u16 rec_inv_sqrt; codel_time_t first_above_time; codel_time_t drop_next; codel_time_t ldelay;}; #define REC_INV_SQRT_BITS (8 * sizeof(u16)) /* or sizeof_in_bits(rec_inv_sqrt) *//* needed shift to get a Q0.32 number from rec_inv_sqrt */#define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS) /** * struct codel_stats - contains codel shared variables and stats * @maxpacket: largest packet we've seen so far * @drop_count: temp count of dropped packets in dequeue() * ecn_mark: number of packets we ECN marked instead of dropping */struct codel_stats { u32 maxpacket; u32 drop_count; u32 ecn_mark;}; static void codel_params_init(struct codel_params *params){ params->interval = MS2TIME(100); params->target = MS2TIME(5); params->ecn = false;} static void codel_vars_init(struct codel_vars *vars){ memset(vars, 0, sizeof(*vars));} static void codel_stats_init(struct codel_stats *stats){ stats->maxpacket = 256;} /* * http://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Iterative_methods_for_reciprocal_square_roots * new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2) * * Here, invsqrt is a fixed point number (< 1.0), 32bit mantissa, aka Q0.32 */static void codel_Newton_step(struct codel_vars *vars){ u32 invsqrt = ((u32)vars->rec_inv_sqrt) << REC_INV_SQRT_SHIFT; u32 invsqrt2 = ((u64)invsqrt * invsqrt) >> 32; u64 val = (3LL << 32) - ((u64)vars->count * invsqrt2); val >>= 2; /* avoid overflow in following multiply */ val = (val * invsqrt) >> (32 - 2 + 1); vars->rec_inv_sqrt = val >> REC_INV_SQRT_SHIFT;} /* * CoDel control_law is t + interval/sqrt(count) * We maintain in rec_inv_sqrt the reciprocal value of sqrt(count) to avoid * both sqrt() and divide operation. */static codel_time_t codel_control_law(codel_time_t t, codel_time_t interval, u32 rec_inv_sqrt){ return t + reciprocal_scale(interval, rec_inv_sqrt << REC_INV_SQRT_SHIFT);} static bool codel_should_drop(const struct sk_buff *skb, struct Qdisc *sch, struct codel_vars *vars, struct codel_params *params, struct codel_stats *stats, codel_time_t now){ bool ok_to_drop; if (!skb) { vars->first_above_time = 0; return false; } vars->ldelay = now - codel_get_enqueue_time(skb); sch->qstats.backlog -= qdisc_pkt_len(skb); if (unlikely(qdisc_pkt_len(skb) > stats->maxpacket)) stats->maxpacket = qdisc_pkt_len(skb); if (codel_time_before(vars->ldelay, params->target) || sch->qstats.backlog <= stats->maxpacket) { /* went below - stay below for at least interval */ vars->first_above_time = 0; return false; } ok_to_drop = false; if (vars->first_above_time == 0) { /* just went above from below. If we stay above * for at least interval we'll say it's ok to drop */ vars->first_above_time = now + params->interval; } else if (codel_time_after(now, vars->first_above_time)) { ok_to_drop = true; } return ok_to_drop;} typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars, struct Qdisc *sch); static struct sk_buff *codel_dequeue(struct Qdisc *sch, struct codel_params *params, struct codel_vars *vars, struct codel_stats *stats, codel_skb_dequeue_t dequeue_func){ struct sk_buff *skb = dequeue_func(vars, sch); codel_time_t now; bool drop; if (!skb) { vars->dropping = false; return skb; } now = codel_get_time(); drop = codel_should_drop(skb, sch, vars, params, stats, now); if (vars->dropping) { if (!drop) { /* sojourn time below target - leave dropping state */ vars->dropping = false; } else if (codel_time_after_eq(now, vars->drop_next)) { /* It's time for the next drop. Drop the current * packet and dequeue the next. The dequeue might * take us out of dropping state. * If not, schedule the next drop. * A large backlog might result in drop rates so high * that the next drop should happen now, * hence the while loop. */ while (vars->dropping && codel_time_after_eq(now, vars->drop_next)) { vars->count++; /* dont care of possible wrap * since there is no more divide */ codel_Newton_step(vars); if (params->ecn && INET_ECN_set_ce(skb)) { stats->ecn_mark++; vars->drop_next = codel_control_law(vars->drop_next, params->interval, vars->rec_inv_sqrt); goto end; } qdisc_drop(skb, sch); stats->drop_count++; skb = dequeue_func(vars, sch); if (!codel_should_drop(skb, sch, vars, params, stats, now)) { /* leave dropping state */ vars->dropping = false; } else { /* and schedule the next drop */ vars->drop_next = codel_control_law(vars->drop_next, params->interval, vars->rec_inv_sqrt); } } } } else if (drop) { u32 delta; if (params->ecn && INET_ECN_set_ce(skb)) { stats->ecn_mark++; } else { qdisc_drop(skb, sch); stats->drop_count++; skb = dequeue_func(vars, sch); drop = codel_should_drop(skb, sch, vars, params, stats, now); } vars->dropping = true; /* if min went above target close to when we last went below it * assume that the drop rate that controlled the queue on the * last cycle is a good starting point to control it now. */ delta = vars->count - vars->lastcount; if (delta > 1 && codel_time_before(now - vars->drop_next, 16 * params->interval)) { vars->count = delta; /* we dont care if rec_inv_sqrt approximation * is not very precise : * Next Newton steps will correct it quadratically. */ codel_Newton_step(vars); } else { vars->count = 1; vars->rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT; } vars->lastcount = vars->count; vars->drop_next = codel_control_law(now, params->interval, vars->rec_inv_sqrt); }end: return skb;}#endif
#ifndef __NET_SCHED_CODEL_H
#define __NET_SCHED_CODEL_H
/*
* Codel - The Controlled-Delay Active Queue Management algorithm
*
* Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com>
* Copyright (C) 2011-2012 Van Jacobson <van@pollere.net>
* Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net>
* Copyright (C) 2012 Eric Dumazet <edumazet@google.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions, and the following disclaimer,
* without modification.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* Alternatively, provided that this notice is retained in full, this
* software may be distributed under the terms of the GNU General
* Public License ("GPL") version 2, in which case the provisions of the
* GPL apply INSTEAD OF those given above.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
*/
#include <linux/types.h>
#include <linux/ktime.h>
#include <linux/skbuff.h>
#include <net/pkt_sched.h>
#include <net/inet_ecn.h>
/* Controlling Queue Delay (CoDel) algorithm
* =========================================
* Source : Kathleen Nichols and Van Jacobson
* http://queue.acm.org/detail.cfm?id=2209336
*
* Implemented on linux by Dave Taht and Eric Dumazet
*/
/* CoDel uses a 1024 nsec clock, encoded in u32
* This gives a range of 2199 seconds, because of signed compares
*/
typedef u32 codel_time_t;
typedef s32 codel_tdiff_t;
#define CODEL_SHIFT 10
#define MS2TIME(a) ((a * NSEC_PER_MSEC) >> CODEL_SHIFT)
static inline codel_time_t codel_get_time(void)
{
u64 ns = ktime_get_ns();
return ns >> CODEL_SHIFT;
}
/* Dealing with timer wrapping, according to RFC 1982, as desc in wikipedia:
* https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution
* codel_time_after(a,b) returns true if the time a is after time b.
*/
#define codel_time_after(a, b) \
(typecheck(codel_time_t, a) && \
typecheck(codel_time_t, b) && \
((s32)((a) - (b)) > 0))
#define codel_time_before(a, b) codel_time_after(b, a)
#define codel_time_after_eq(a, b) \
(typecheck(codel_time_t, a) && \
typecheck(codel_time_t, b) && \
((s32)((a) - (b)) >= 0))
#define codel_time_before_eq(a, b) codel_time_after_eq(b, a)
/* Qdiscs using codel plugin must use codel_skb_cb in their own cb[] */
struct codel_skb_cb {
codel_time_t enqueue_time;
};
static struct codel_skb_cb *get_codel_cb(const struct sk_buff *skb)
{
qdisc_cb_private_validate(skb, sizeof(struct codel_skb_cb));
return (struct codel_skb_cb *)qdisc_skb_cb(skb)->data;
}
static codel_time_t codel_get_enqueue_time(const struct sk_buff *skb)
{
return get_codel_cb(skb)->enqueue_time;
}
static void codel_set_enqueue_time(struct sk_buff *skb)
{
get_codel_cb(skb)->enqueue_time = codel_get_time();
}
static inline u32 codel_time_to_us(codel_time_t val)
{
u64 valns = ((u64)val << CODEL_SHIFT);
do_div(valns, NSEC_PER_USEC);
return (u32)valns;
}
/**
* struct codel_params - contains codel parameters
* @target: target queue size (in time units)
* @interval: width of moving time window
* @ecn: is Explicit Congestion Notification enabled
*/
struct codel_params {
codel_time_t target;
codel_time_t interval;
bool ecn;
};
/**
* struct codel_vars - contains codel variables
* @count: how many drops we've done since the last time we
* entered dropping state
* @lastcount: count at entry to dropping state
* @dropping: set to true if in dropping state
* @rec_inv_sqrt: reciprocal value of sqrt(count) >> 1
* @first_above_time: when we went (or will go) continuously above target
* for interval
* @drop_next: time to drop next packet, or when we dropped last
* @ldelay: sojourn time of last dequeued packet
*/
struct codel_vars {
u32 count;
u32 lastcount;
bool dropping;
u16 rec_inv_sqrt;
codel_time_t first_above_time;
codel_time_t drop_next;
codel_time_t ldelay;
};
#define REC_INV_SQRT_BITS (8 * sizeof(u16)) /* or sizeof_in_bits(rec_inv_sqrt) */
/* needed shift to get a Q0.32 number from rec_inv_sqrt */
#define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS)
/**
* struct codel_stats - contains codel shared variables and stats
* @maxpacket: largest packet we've seen so far
* @drop_count: temp count of dropped packets in dequeue()
* ecn_mark: number of packets we ECN marked instead of dropping
*/
struct codel_stats {
u32 maxpacket;
u32 drop_count;
u32 ecn_mark;
};
static void codel_params_init(struct codel_params *params)
{
params->interval = MS2TIME(100);
params->target = MS2TIME(5);
params->ecn = false;
}
static void codel_vars_init(struct codel_vars *vars)
{
memset(vars, 0, sizeof(*vars));
}
static void codel_stats_init(struct codel_stats *stats)
{
stats->maxpacket = 256;
}
/*
* http://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Iterative_methods_for_reciprocal_square_roots
* new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2)
*
* Here, invsqrt is a fixed point number (< 1.0), 32bit mantissa, aka Q0.32
*/
static void codel_Newton_step(struct codel_vars *vars)
{
u32 invsqrt = ((u32)vars->rec_inv_sqrt) << REC_INV_SQRT_SHIFT;
u32 invsqrt2 = ((u64)invsqrt * invsqrt) >> 32;
u64 val = (3LL << 32) - ((u64)vars->count * invsqrt2);
val >>= 2; /* avoid overflow in following multiply */
val = (val * invsqrt) >> (32 - 2 + 1);
vars->rec_inv_sqrt = val >> REC_INV_SQRT_SHIFT;
}
/*
* CoDel control_law is t + interval/sqrt(count)
* We maintain in rec_inv_sqrt the reciprocal value of sqrt(count) to avoid
* both sqrt() and divide operation.
*/
static codel_time_t codel_control_law(codel_time_t t,
codel_time_t interval,
u32 rec_inv_sqrt)
{
return t + reciprocal_scale(interval, rec_inv_sqrt << REC_INV_SQRT_SHIFT);
}
static bool codel_should_drop(const struct sk_buff *skb,
struct Qdisc *sch,
struct codel_vars *vars,
struct codel_params *params,
struct codel_stats *stats,
codel_time_t now)
{
bool ok_to_drop;
if (!skb) {
vars->first_above_time = 0;
return false;
}
vars->ldelay = now - codel_get_enqueue_time(skb);
sch->qstats.backlog -= qdisc_pkt_len(skb);
if (unlikely(qdisc_pkt_len(skb) > stats->maxpacket))
stats->maxpacket = qdisc_pkt_len(skb);
if (codel_time_before(vars->ldelay, params->target) ||
sch->qstats.backlog <= stats->maxpacket) {
/* went below - stay below for at least interval */
vars->first_above_time = 0;
return false;
}
ok_to_drop = false;
if (vars->first_above_time == 0) {
/* just went above from below. If we stay above
* for at least interval we'll say it's ok to drop
*/
vars->first_above_time = now + params->interval;
} else if (codel_time_after(now, vars->first_above_time)) {
ok_to_drop = true;
}
return ok_to_drop;
}
typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars,
struct Qdisc *sch);
static struct sk_buff *codel_dequeue(struct Qdisc *sch,
struct codel_params *params,
struct codel_vars *vars,
struct codel_stats *stats,
codel_skb_dequeue_t dequeue_func)
{
struct sk_buff *skb = dequeue_func(vars, sch);
codel_time_t now;
bool drop;
if (!skb) {
vars->dropping = false;
return skb;
}
now = codel_get_time();
drop = codel_should_drop(skb, sch, vars, params, stats, now);
if (vars->dropping) {
if (!drop) {
/* sojourn time below target - leave dropping state */
vars->dropping = false;
} else if (codel_time_after_eq(now, vars->drop_next)) {
/* It's time for the next drop. Drop the current
* packet and dequeue the next. The dequeue might
* take us out of dropping state.
* If not, schedule the next drop.
* A large backlog might result in drop rates so high
* that the next drop should happen now,
* hence the while loop.
*/
while (vars->dropping &&
codel_time_after_eq(now, vars->drop_next)) {
vars->count++; /* dont care of possible wrap
* since there is no more divide
*/
codel_Newton_step(vars);
if (params->ecn && INET_ECN_set_ce(skb)) {
stats->ecn_mark++;
vars->drop_next =
codel_control_law(vars->drop_next,
params->interval,
vars->rec_inv_sqrt);
goto end;
}
qdisc_drop(skb, sch);
stats->drop_count++;
skb = dequeue_func(vars, sch);
if (!codel_should_drop(skb, sch,
vars, params, stats, now)) {
/* leave dropping state */
vars->dropping = false;
} else {
/* and schedule the next drop */
vars->drop_next =
codel_control_law(vars->drop_next,
params->interval,
vars->rec_inv_sqrt);
}
}
}
} else if (drop) {
u32 delta;
if (params->ecn && INET_ECN_set_ce(skb)) {
stats->ecn_mark++;
} else {
qdisc_drop(skb, sch);
stats->drop_count++;
skb = dequeue_func(vars, sch);
drop = codel_should_drop(skb, sch, vars, params,
stats, now);
}
vars->dropping = true;
/* if min went above target close to when we last went below it
* assume that the drop rate that controlled the queue on the
* last cycle is a good starting point to control it now.
*/
delta = vars->count - vars->lastcount;
if (delta > 1 &&
codel_time_before(now - vars->drop_next,
16 * params->interval)) {
vars->count = delta;
/* we dont care if rec_inv_sqrt approximation
* is not very precise :
* Next Newton steps will correct it quadratically.
*/
codel_Newton_step(vars);
} else {
vars->count = 1;
vars->rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
}
vars->lastcount = vars->count;
vars->drop_next = codel_control_law(now, params->interval,
vars->rec_inv_sqrt);
}
end:
return skb;
}
#endif