#ifndef __NET_SCHED_CODEL_IMPL_H#define __NET_SCHED_CODEL_IMPL_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) 2012,2015 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. * */ /* 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 */ #include <net/inet_ecn.h> static void codel_params_init(struct codel_params *params){ params->interval = MS2TIME(100); params->target = MS2TIME(5); params->ce_threshold = CODEL_DISABLED_THRESHOLD; params->ce_threshold_mask = 0; params->ce_threshold_selector = 0; 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 = 0;} /* * 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, void *ctx, struct codel_vars *vars, struct codel_params *params, struct codel_stats *stats, codel_skb_len_t skb_len_func, codel_skb_time_t skb_time_func, u32 *backlog, codel_time_t now){ bool ok_to_drop; u32 skb_len; if (!skb) { vars->first_above_time = 0; return false; } skb_len = skb_len_func(skb); WRITE_ONCE(vars->ldelay, now - skb_time_func(skb)); if (unlikely(skb_len > stats->maxpacket)) WRITE_ONCE(stats->maxpacket, skb_len); if (codel_time_before(vars->ldelay, params->target) || *backlog <= params->mtu) { /* 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;} static struct sk_buff *codel_dequeue(void *ctx, u32 *backlog, struct codel_params *params, struct codel_vars *vars, struct codel_stats *stats, codel_skb_len_t skb_len_func, codel_skb_time_t skb_time_func, codel_skb_drop_t drop_func, codel_skb_dequeue_t dequeue_func){ struct sk_buff *skb = dequeue_func(vars, ctx); codel_time_t now; bool drop; if (!skb) { vars->first_above_time = 0; WRITE_ONCE(vars->dropping, false); return skb; } now = codel_get_time(); drop = codel_should_drop(skb, ctx, vars, params, stats, skb_len_func, skb_time_func, backlog, now); if (vars->dropping) { if (!drop) { /* sojourn time below target - leave dropping state */ WRITE_ONCE(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)) { /* dont care of possible wrap * since there is no more divide. */ WRITE_ONCE(vars->count, vars->count + 1); codel_Newton_step(vars); if (params->ecn && INET_ECN_set_ce(skb)) { WRITE_ONCE(stats->ecn_mark, stats->ecn_mark + 1); WRITE_ONCE(vars->drop_next, codel_control_law(vars->drop_next, params->interval, vars->rec_inv_sqrt)); goto end; } stats->drop_len += skb_len_func(skb); drop_func(skb, ctx); stats->drop_count++; skb = dequeue_func(vars, ctx); if (!codel_should_drop(skb, ctx, vars, params, stats, skb_len_func, skb_time_func, backlog, now)) { /* leave dropping state */ WRITE_ONCE(vars->dropping, false); } else { /* and schedule the next drop */ WRITE_ONCE(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)) { WRITE_ONCE(stats->ecn_mark, stats->ecn_mark + 1); } else { stats->drop_len += skb_len_func(skb); drop_func(skb, ctx); stats->drop_count++; skb = dequeue_func(vars, ctx); drop = codel_should_drop(skb, ctx, vars, params, stats, skb_len_func, skb_time_func, backlog, now); } WRITE_ONCE(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)) { WRITE_ONCE(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 { WRITE_ONCE(vars->count, 1); vars->rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT; } WRITE_ONCE(vars->lastcount, vars->count); WRITE_ONCE(vars->drop_next, codel_control_law(now, params->interval, vars->rec_inv_sqrt)); }end: if (skb && codel_time_after(vars->ldelay, params->ce_threshold)) { bool set_ce = true; if (params->ce_threshold_mask) { int dsfield = skb_get_dsfield(skb); set_ce = (dsfield >= 0 && (((u8)dsfield & params->ce_threshold_mask) == params->ce_threshold_selector)); } if (set_ce && INET_ECN_set_ce(skb)) WRITE_ONCE(stats->ce_mark, stats->ce_mark + 1); } return skb;} #endif
#ifndef __NET_SCHED_CODEL_IMPL_H
#define __NET_SCHED_CODEL_IMPL_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) 2012,2015 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.
*
*/
/* 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
*/
#include <net/inet_ecn.h>
static void codel_params_init(struct codel_params *params)
{
params->interval = MS2TIME(100);
params->target = MS2TIME(5);
params->ce_threshold = CODEL_DISABLED_THRESHOLD;
params->ce_threshold_mask = 0;
params->ce_threshold_selector = 0;
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 = 0;
}
/*
* 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,
void *ctx,
struct codel_vars *vars,
struct codel_params *params,
struct codel_stats *stats,
codel_skb_len_t skb_len_func,
codel_skb_time_t skb_time_func,
u32 *backlog,
codel_time_t now)
{
bool ok_to_drop;
u32 skb_len;
if (!skb) {
vars->first_above_time = 0;
return false;
}
skb_len = skb_len_func(skb);
WRITE_ONCE(vars->ldelay, now - skb_time_func(skb));
if (unlikely(skb_len > stats->maxpacket))
WRITE_ONCE(stats->maxpacket, skb_len);
if (codel_time_before(vars->ldelay, params->target) ||
*backlog <= params->mtu) {
/* 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;
}
static struct sk_buff *codel_dequeue(void *ctx,
u32 *backlog,
struct codel_params *params,
struct codel_vars *vars,
struct codel_stats *stats,
codel_skb_len_t skb_len_func,
codel_skb_time_t skb_time_func,
codel_skb_drop_t drop_func,
codel_skb_dequeue_t dequeue_func)
{
struct sk_buff *skb = dequeue_func(vars, ctx);
codel_time_t now;
bool drop;
if (!skb) {
vars->first_above_time = 0;
WRITE_ONCE(vars->dropping, false);
return skb;
}
now = codel_get_time();
drop = codel_should_drop(skb, ctx, vars, params, stats,
skb_len_func, skb_time_func, backlog, now);
if (vars->dropping) {
if (!drop) {
/* sojourn time below target - leave dropping state */
WRITE_ONCE(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)) {
/* dont care of possible wrap
* since there is no more divide.
*/
WRITE_ONCE(vars->count, vars->count + 1);
codel_Newton_step(vars);
if (params->ecn && INET_ECN_set_ce(skb)) {
WRITE_ONCE(stats->ecn_mark,
stats->ecn_mark + 1);
WRITE_ONCE(vars->drop_next,
codel_control_law(vars->drop_next,
params->interval,
vars->rec_inv_sqrt));
goto end;
}
stats->drop_len += skb_len_func(skb);
drop_func(skb, ctx);
stats->drop_count++;
skb = dequeue_func(vars, ctx);
if (!codel_should_drop(skb, ctx,
vars, params, stats,
skb_len_func,
skb_time_func,
backlog, now)) {
/* leave dropping state */
WRITE_ONCE(vars->dropping, false);
} else {
/* and schedule the next drop */
WRITE_ONCE(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)) {
WRITE_ONCE(stats->ecn_mark, stats->ecn_mark + 1);
} else {
stats->drop_len += skb_len_func(skb);
drop_func(skb, ctx);
stats->drop_count++;
skb = dequeue_func(vars, ctx);
drop = codel_should_drop(skb, ctx, vars, params,
stats, skb_len_func,
skb_time_func, backlog, now);
}
WRITE_ONCE(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)) {
WRITE_ONCE(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 {
WRITE_ONCE(vars->count, 1);
vars->rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
}
WRITE_ONCE(vars->lastcount, vars->count);
WRITE_ONCE(vars->drop_next,
codel_control_law(now, params->interval,
vars->rec_inv_sqrt));
}
end:
if (skb && codel_time_after(vars->ldelay, params->ce_threshold)) {
bool set_ce = true;
if (params->ce_threshold_mask) {
int dsfield = skb_get_dsfield(skb);
set_ce = (dsfield >= 0 &&
(((u8)dsfield & params->ce_threshold_mask) ==
params->ce_threshold_selector));
}
if (set_ce && INET_ECN_set_ce(skb))
WRITE_ONCE(stats->ce_mark, stats->ce_mark + 1);
}
return skb;
}
#endif