[Codel] [Bloat] [PATCH v12] codel: Controlled Delay AQM
Josh Hunt
joshua.hunt at berkeley.edu
Wed May 9 12:32:33 EDT 2012
On Wed, May 9, 2012 at 8:50 AM, Eric Dumazet <eric.dumazet at gmail.com> wrote:
> From: Eric Dumazet <edumazet at google.com>
>
> An implementation of CoDel AQM, from Kathleen Nichols and Van Jacobson.
>
> http://queue.acm.org/detail.cfm?id=2209336
>
> Based on initial work from Dave Taht.
>
> Refactored to help future codel inclusion as plugin for other linux
> qdisc (SFQ), like done with RED plugin.
>
> Tested up to 10Gb speeds with no particular problems.
>
> Signed-off-by: Eric Dumazet <edumazet at google.com>
> Signed-off-by: Dave Taht <dave.taht at bufferbloat.net>
> Cc: Kathleen Nichols <nichols at pollere.com>
> Cc: Van Jacobson <van at pollere.net>
> ---
> v12: algo changes after Kathleen & Van last updates
> - introduction of lastcount.
> - minbytes renamed to maxpacket.
> - maxpacket automatically learns biggest packet size.
> - ldelay record sojourn time of last dequeued packet.
> - various changes, better comments...
>
> I hope this is the last version before upstream submission (netdev)
> I'll send the iproute2 patch as well.
>
> include/linux/pkt_sched.h | 28 +++
> include/net/codel.h | 325 ++++++++++++++++++++++++++++++++++++
> net/sched/Kconfig | 11 +
> net/sched/Makefile | 1
> net/sched/sch_codel.c | 272 ++++++++++++++++++++++++++++++
> 5 files changed, 637 insertions(+)
>
> diff --git a/include/linux/pkt_sched.h b/include/linux/pkt_sched.h
> index ffe975c..453dd2c 100644
> --- a/include/linux/pkt_sched.h
> +++ b/include/linux/pkt_sched.h
> @@ -655,4 +655,32 @@ struct tc_qfq_stats {
> __u32 lmax;
> };
>
> +/* CODEL */
> +
> +enum {
> + TCA_CODEL_UNSPEC,
> + TCA_CODEL_TARGET,
> + TCA_CODEL_LIMIT,
> + TCA_CODEL_INTERVAL,
> + TCA_CODEL_ECN,
> + __TCA_CODEL_MAX
> +};
> +
> +#define TCA_CODEL_MAX (__TCA_CODEL_MAX - 1)
> +
> +struct tc_codel_xstats {
> + __u32 maxpacket; /* largest packet we've seen so far */
> + __u32 count;
> + __u32 lastcount;
> + __u32 ldelay; /* in-queue delay seen by most recently dequeued packet */
> + __u32 drop_next;
> + __u32 drop_overlimit;
> + __u32 ecn_mark;
> + __u32 dropping;
> + __u32 state1;
> + __u32 state2;
> + __u32 state3;
> + __u32 states;
> +};
> +
> #endif
> diff --git a/include/net/codel.h b/include/net/codel.h
> new file mode 100644
> index 0000000..565c1fe
> --- /dev/null
> +++ b/include/net/codel.h
> @@ -0,0 +1,325 @@
> +#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 at pollere.com>
> + * Copyright (C) 2011-2012 Van Jacobson <van at pollere.net>
> + * Copyright (C) 2012 Michael D. Taht <dave.taht at bufferbloat.net>
> + * Copyright (C) 2012 Eric Dumazet <edumazet at 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/bug.h>
> +#include <linux/ktime.h>
> +#include <net/inet_ecn.h>
> +
> +/* Controlling Queue Delay (CoDel) algorithm
> + * =========================================
> + * Source : Kathleen Nichols and Van Jacobson
> + * http://queue.acm.org/detail.cfm?id=2209396
This link is dead. Looks like it's a typo and should be:
http://queue.acm.org/detail.cfm?id=2209336
Josh
> + *
> + * 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;
> +#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_to_ns(ktime_get());
> +
> + return ns >> CODEL_SHIFT;
> +}
> +
> +#define codel_time_after(a, b) ((s32)(a) - (s32)(b) > 0)
> +#define codel_time_after_eq(a, b) ((s32)(a) - (s32)(b) >= 0)
> +#define codel_time_before(a, b) ((s32)(a) - (s32)(b) < 0)
> +#define codel_time_before_eq(a, b) ((s32)(a) - (s32)(b) <= 0)
> +
> +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 {
> + u32 maxpacket; /* largest packet we've seen so far */
> + codel_time_t target; /* target queue size (in time units) */
> + codel_time_t interval; /* width of moving time window */
> + bool ecn; /* is ECN enabled */
> +};
> +
> +struct codel_vars {
> + u32 count; /* how many drops we've done since the last time
> + * we entered dropping state
> + */
> + u32 lastcount; /* count at entry to dropping state */
> + bool dropping; /* set to true id in dropping state */
> +
> + codel_time_t first_above_time; /* when we went (or will go) continuously
> + * above target for interval
> + */
> + codel_time_t drop_next; /* time to drop next packet, or when we dropped last */
> + codel_time_t ldelay; /* sojourn time of last dequeued packet */
> +};
> +
> +/* contains stats and some shared info */
> +struct codel_stats {
> + struct Qdisc *sch;
> + u32 drop_count; /* temp count of dropped packets in dequeue() */
> +
> + u32 ecn_mark; /* number of packets we ECN marked instead of dropping */
> + u32 states; /* number of codel_dequeue() calls */
> + u32 state1; /* number of times ok_to_drop was set to true */
> + u32 state2;
> + u32 state3;
> +};
> +
> +static void codel_params_init(struct codel_params *params,
> + const struct Qdisc *sch)
> +{
> + params->maxpacket = 256;
> + params->interval = MS2TIME(100);
> + params->target = MS2TIME(5);
> + params->ecn = false;
> +}
> +
> +static void codel_vars_init(struct codel_vars *vars)
> +{
> + vars->drop_next = 0;
> + vars->first_above_time = 0;
> + vars->dropping = false; /* exit dropping state */
> + vars->count = 0;
> + vars->lastcount = 0;
> +}
> +
> +static void codel_stats_init(struct codel_stats *stats,
> + struct Qdisc *sch)
> +{
> + stats->sch = sch; /* back pointer for qdisc_drop() calls */
> +}
> +
> +/* return interval/sqrt(x) with good precision */
> +static u32 codel_inv_sqrt(u32 _interval, u32 _x)
> +{
> + u64 interval = _interval;
> + unsigned long x = _x;
> +
> + /* Scale operands for max precision */
> +
> +#if BITS_PER_LONG == 64
> + x <<= 32; /* On 64bit arches, we can prescale x by 32bits */
> + interval <<= 16;
> +#endif
> +
> + while (x < (1UL << (BITS_PER_LONG - 2))) {
> + x <<= 2;
> + interval <<= 1;
> + }
> + do_div(interval, int_sqrt(x));
> + return (u32)interval;
> +}
> +
> +static codel_time_t codel_control_law(codel_time_t t,
> + codel_time_t interval,
> + u32 count)
> +{
> + return t + codel_inv_sqrt(interval, count);
> +}
> +
> +
> +static bool codel_should_drop(struct sk_buff *skb,
> + unsigned int *backlog,
> + 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);
> + *backlog -= qdisc_pkt_len(skb);
> +
> + if (unlikely(qdisc_pkt_len(skb) > params->maxpacket))
> + params->maxpacket = qdisc_pkt_len(skb);
> +
> + if (codel_time_before(vars->ldelay, params->target) ||
> + *backlog <= params->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;
> + stats->state1++;
> + }
> + 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 codel_params *params,
> + struct codel_vars *vars,
> + struct codel_stats *stats,
> + codel_skb_dequeue_t dequeue_func,
> + u32 *backlog)
> +{
> + struct sk_buff *skb = dequeue_func(vars, stats->sch);
> + codel_time_t now;
> + bool drop;
> +
> + stats->states++;
> + if (!skb) {
> + vars->dropping = false;
> + return skb;
> + }
> + now = codel_get_time();
> + drop = codel_should_drop(skb, backlog,
> + 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)) {
> + stats->state2++;
> + /* 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++;
> + if (params->ecn && INET_ECN_set_ce(skb)) {
> + stats->ecn_mark++;
> + vars->drop_next =
> + codel_control_law(vars->drop_next,
> + params->interval,
> + vars->count);
> + goto end;
> + }
> + qdisc_drop(skb, stats->sch);
> + stats->drop_count++;
> + skb = dequeue_func(vars, stats->sch);
> + if (!codel_should_drop(skb, backlog,
> + 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->count);
> + }
> + }
> + }
> + } else if (drop) {
> + if (params->ecn && INET_ECN_set_ce(skb)) {
> + stats->ecn_mark++;
> + } else {
> + qdisc_drop(skb, stats->sch);
> + stats->drop_count++;
> +
> + skb = dequeue_func(vars, stats->sch);
> + drop = codel_should_drop(skb, backlog, vars, params,
> + stats, now);
> + }
> + vars->dropping = true;
> + stats->state3++;
> + /*
> + * 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.
> + */
> + if (codel_time_before(now - vars->drop_next,
> + 16 * params->interval)) {
> + vars->count = vars->count - vars->lastcount + 1;
> + } else {
> + vars->count = 1;
> + }
> + vars->lastcount = vars->count;
> + vars->drop_next = codel_control_law(now, params->interval,
> + vars->count);
> + }
> +end:
> + return skb;
> +}
> +#endif
> diff --git a/net/sched/Kconfig b/net/sched/Kconfig
> index 75b58f8..fadd252 100644
> --- a/net/sched/Kconfig
> +++ b/net/sched/Kconfig
> @@ -250,6 +250,17 @@ config NET_SCH_QFQ
>
> If unsure, say N.
>
> +config NET_SCH_CODEL
> + tristate "Controlled Delay AQM (CODEL)"
> + help
> + Say Y here if you want to use the Controlled Delay (CODEL)
> + packet scheduling algorithm.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called sch_codel.
> +
> + If unsure, say N.
> +
> config NET_SCH_INGRESS
> tristate "Ingress Qdisc"
> depends on NET_CLS_ACT
> diff --git a/net/sched/Makefile b/net/sched/Makefile
> index 8cdf4e2..30fab03 100644
> --- a/net/sched/Makefile
> +++ b/net/sched/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_NET_SCH_PLUG) += sch_plug.o
> obj-$(CONFIG_NET_SCH_MQPRIO) += sch_mqprio.o
> obj-$(CONFIG_NET_SCH_CHOKE) += sch_choke.o
> obj-$(CONFIG_NET_SCH_QFQ) += sch_qfq.o
> +obj-$(CONFIG_NET_SCH_CODEL) += sch_codel.o
>
> obj-$(CONFIG_NET_CLS_U32) += cls_u32.o
> obj-$(CONFIG_NET_CLS_ROUTE4) += cls_route.o
> diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c
> new file mode 100644
> index 0000000..3112afa
> --- /dev/null
> +++ b/net/sched/sch_codel.c
> @@ -0,0 +1,272 @@
> +/*
> + * Codel - The Controlled-Delay Active Queue Management algorithm
> + *
> + * Copyright (C) 2011-2012 Kathleen Nichols <nichols at pollere.com>
> + * Copyright (C) 2011-2012 Van Jacobson <van at pollere.net>
> + *
> + * Implemented on linux by :
> + * Copyright (C) 2012 Michael D. Taht <dave.taht at bufferbloat.net>
> + * Copyright (C) 2012 Eric Dumazet <edumazet at 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/module.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/kernel.h>
> +#include <linux/errno.h>
> +#include <linux/skbuff.h>
> +#include <net/pkt_sched.h>
> +#include <net/codel.h>
> +
> +
> +#define DEFAULT_CODEL_LIMIT 1000
> +
> +struct codel_sched_data {
> + struct codel_params params;
> + struct codel_vars vars;
> + struct codel_stats stats;
> + u32 drop_overlimit;
> +};
> +
> +/* This is the specific function called from codel_dequeue()
> + * to dequeue a packet from queue. Note: backlog is handled in
> + * codel, we dont need to reduce it here.
> + */
> +static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
> +{
> + struct sk_buff *skb = __skb_dequeue(&sch->q);
> +
> + prefetch(&skb->end); /* we'll need skb_shinfo() */
> + return skb;
> +}
> +
> +static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch)
> +{
> + struct codel_sched_data *q = qdisc_priv(sch);
> + struct sk_buff *skb;
> +
> + skb = codel_dequeue(&q->params, &q->vars, &q->stats,
> + dequeue, &sch->qstats.backlog);
> + /* We cant call qdisc_tree_decrease_qlen() if our qlen is 0,
> + * or HTB crashes. Defer it for next round.
> + */
> + if (q->stats.drop_count && sch->q.qlen) {
> + qdisc_tree_decrease_qlen(sch, q->stats.drop_count);
> + q->stats.drop_count = 0;
> + }
> + if (skb)
> + qdisc_bstats_update(sch, skb);
> + return skb;
> +}
> +
> +static int codel_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
> +{
> + struct codel_sched_data *q;
> +
> + if (likely(qdisc_qlen(sch) < sch->limit)) {
> + codel_set_enqueue_time(skb);
> + return qdisc_enqueue_tail(skb, sch);
> + }
> + q = qdisc_priv(sch);
> + q->drop_overlimit++;
> + return qdisc_drop(skb, sch);
> +}
> +
> +static const struct nla_policy codel_policy[TCA_CODEL_MAX + 1] = {
> + [TCA_CODEL_TARGET] = { .type = NLA_U32 },
> + [TCA_CODEL_LIMIT] = { .type = NLA_U32 },
> + [TCA_CODEL_INTERVAL] = { .type = NLA_U32 },
> + [TCA_CODEL_ECN] = { .type = NLA_U32 },
> +};
> +
> +static int codel_change(struct Qdisc *sch, struct nlattr *opt)
> +{
> + struct codel_sched_data *q = qdisc_priv(sch);
> + struct nlattr *tb[TCA_CODEL_MAX + 1];
> + unsigned int qlen;
> + int err;
> +
> + if (!opt)
> + return -EINVAL;
> +
> + err = nla_parse_nested(tb, TCA_CODEL_MAX, opt, codel_policy);
> + if (err < 0)
> + return err;
> +
> + sch_tree_lock(sch);
> + if (tb[TCA_CODEL_TARGET]) {
> + u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]);
> +
> + q->params.target = ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT;
> + }
> + if (tb[TCA_CODEL_INTERVAL]) {
> + u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]);
> +
> + q->params.interval = ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT;
> + }
> + if (tb[TCA_CODEL_LIMIT])
> + sch->limit = nla_get_u32(tb[TCA_CODEL_LIMIT]);
> +
> + if (tb[TCA_CODEL_ECN])
> + q->params.ecn = !!nla_get_u32(tb[TCA_CODEL_ECN]);
> +
> + qlen = sch->q.qlen;
> + while (sch->q.qlen > sch->limit) {
> + struct sk_buff *skb = __skb_dequeue(&sch->q);
> +
> + sch->qstats.backlog -= qdisc_pkt_len(skb);
> + qdisc_drop(skb, sch);
> + }
> + qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen);
> +
> + sch_tree_unlock(sch);
> + return 0;
> +}
> +
> +static int codel_init(struct Qdisc *sch, struct nlattr *opt)
> +{
> + struct codel_sched_data *q = qdisc_priv(sch);
> +
> + /* It should be possible to run with no limit,
> + * with infinite memory :)
> + */
> + sch->limit = DEFAULT_CODEL_LIMIT;
> +
> + codel_params_init(&q->params, sch);
> + codel_vars_init(&q->vars);
> + codel_stats_init(&q->stats, sch);
> +
> + if (opt) {
> + int err = codel_change(sch, opt);
> +
> + if (err)
> + return err;
> + }
> +
> + if (sch->limit >= 1)
> + sch->flags |= TCQ_F_CAN_BYPASS;
> + else
> + sch->flags &= ~TCQ_F_CAN_BYPASS;
> +
> + return 0;
> +}
> +
> +static int codel_dump(struct Qdisc *sch, struct sk_buff *skb)
> +{
> + struct codel_sched_data *q = qdisc_priv(sch);
> + struct nlattr *opts;
> +
> + opts = nla_nest_start(skb, TCA_OPTIONS);
> + if (opts == NULL)
> + goto nla_put_failure;
> +
> + if (nla_put_u32(skb, TCA_CODEL_TARGET,
> + codel_time_to_us(q->params.target)) ||
> + nla_put_u32(skb, TCA_CODEL_LIMIT,
> + sch->limit) ||
> + nla_put_u32(skb, TCA_CODEL_INTERVAL,
> + codel_time_to_us(q->params.interval)) ||
> + nla_put_u32(skb, TCA_CODEL_ECN,
> + q->params.ecn))
> + goto nla_put_failure;
> +
> + return nla_nest_end(skb, opts);
> +
> +nla_put_failure:
> + nla_nest_cancel(skb, opts);
> + return -1;
> +}
> +
> +static int codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
> +{
> + const struct codel_sched_data *q = qdisc_priv(sch);
> + struct tc_codel_xstats st = {
> + .maxpacket = q->params.maxpacket,
> + .count = q->vars.count,
> + .lastcount = q->vars.lastcount,
> + .states = q->stats.states,
> + .state1 = q->stats.state1,
> + .state2 = q->stats.state2,
> + .state3 = q->stats.state3,
> + .drop_overlimit = q->drop_overlimit,
> + .ldelay = codel_time_to_us(q->vars.ldelay),
> + .dropping = q->vars.dropping,
> + .ecn_mark = q->stats.ecn_mark,
> + };
> +
> + if (q->vars.dropping && q->vars.drop_next)
> + st.drop_next = codel_time_to_us(q->vars.drop_next -
> + codel_get_time());
> +
> + return gnet_stats_copy_app(d, &st, sizeof(st));
> +}
> +
> +static void codel_reset(struct Qdisc *sch)
> +{
> + struct codel_sched_data *q = qdisc_priv(sch);
> +
> + qdisc_reset_queue(sch);
> + codel_vars_init(&q->vars);
> +}
> +
> +static struct Qdisc_ops codel_qdisc_ops __read_mostly = {
> + .id = "codel",
> + .priv_size = sizeof(struct codel_sched_data),
> +
> + .enqueue = codel_qdisc_enqueue,
> + .dequeue = codel_qdisc_dequeue,
> + .peek = qdisc_peek_dequeued,
> + .init = codel_init,
> + .reset = codel_reset,
> + .change = codel_change,
> + .dump = codel_dump,
> + .dump_stats = codel_dump_stats,
> + .owner = THIS_MODULE,
> +};
> +
> +static int __init codel_module_init(void)
> +{
> + return register_qdisc(&codel_qdisc_ops);
> +}
> +static void __exit codel_module_exit(void)
> +{
> + unregister_qdisc(&codel_qdisc_ops);
> +}
> +module_init(codel_module_init)
> +module_exit(codel_module_exit)
> +
> +MODULE_DESCRIPTION("Controlled Delay queue discipline");
> +MODULE_AUTHOR("Dave Taht");
> +MODULE_AUTHOR("Eric Dumazet");
> +MODULE_LICENSE("Dual BSD/GPL");
>
>
> _______________________________________________
> Bloat mailing list
> Bloat at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat
More information about the Codel
mailing list