diff options
| -rw-r--r-- | include/uapi/linux/pkt_sched.h | 25 | ||||
| -rw-r--r-- | net/sched/Kconfig | 13 | ||||
| -rw-r--r-- | net/sched/Makefile | 1 | ||||
| -rw-r--r-- | net/sched/sch_pie.c | 555 |
4 files changed, 594 insertions, 0 deletions
diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index 77eb331810b..d62316baae9 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -818,4 +818,29 @@ struct tc_hhf_xstats { __u32 hh_tot_count; /* number of captured heavy-hitters so far */ __u32 hh_cur_count; /* number of current heavy-hitters */ }; + +/* PIE */ +enum { + TCA_PIE_UNSPEC, + TCA_PIE_TARGET, + TCA_PIE_LIMIT, + TCA_PIE_TUPDATE, + TCA_PIE_ALPHA, + TCA_PIE_BETA, + TCA_PIE_ECN, + TCA_PIE_BYTEMODE, + __TCA_PIE_MAX +}; +#define TCA_PIE_MAX (__TCA_PIE_MAX - 1) + +struct tc_pie_xstats { + __u32 prob; /* current probability */ + __u32 delay; /* current delay in ms */ + __u32 avg_dq_rate; /* current average dq_rate in bits/pie_time */ + __u32 packets_in; /* total number of packets enqueued */ + __u32 dropped; /* packets dropped due to pie_action */ + __u32 overlimit; /* dropped due to lack of space in queue */ + __u32 maxq; /* maximum queue size */ + __u32 ecn_mark; /* packets marked with ecn*/ +}; #endif diff --git a/net/sched/Kconfig b/net/sched/Kconfig index d3d7a0a66e2..a1a8e29e5fc 100644 --- a/net/sched/Kconfig +++ b/net/sched/Kconfig @@ -295,6 +295,19 @@ config NET_SCH_HHF To compile this driver as a module, choose M here: the module will be called sch_hhf. +config NET_SCH_PIE + tristate "Proportional Integral controller Enhanced (PIE) scheduler" + help + Say Y here if you want to use the Proportional Integral controller + Enhanced scheduler packet scheduling algorithm. + For more information, please see + http://tools.ietf.org/html/draft-pan-tsvwg-pie-00 + + To compile this driver as a module, choose M here: the module + will be called sch_pie. + + 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 3442e5fbc4d..0a869a11f3e 100644 --- a/net/sched/Makefile +++ b/net/sched/Makefile @@ -41,6 +41,7 @@ obj-$(CONFIG_NET_SCH_CODEL) += sch_codel.o obj-$(CONFIG_NET_SCH_FQ_CODEL) += sch_fq_codel.o obj-$(CONFIG_NET_SCH_FQ) += sch_fq.o obj-$(CONFIG_NET_SCH_HHF) += sch_hhf.o +obj-$(CONFIG_NET_SCH_PIE) += sch_pie.o obj-$(CONFIG_NET_CLS_U32) += cls_u32.o obj-$(CONFIG_NET_CLS_ROUTE4) += cls_route.o diff --git a/net/sched/sch_pie.c b/net/sched/sch_pie.c new file mode 100644 index 00000000000..fe65340c8eb --- /dev/null +++ b/net/sched/sch_pie.c @@ -0,0 +1,555 @@ +/* Copyright (C) 2013 Cisco Systems, Inc, 2013. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * Author: Vijay Subramanian <vijaynsu@cisco.com> + * Author: Mythili Prabhu <mysuryan@cisco.com> + * + * ECN support is added by Naeem Khademi <naeemk@ifi.uio.no> + * University of Oslo, Norway. + */ + +#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/inet_ecn.h> + +#define QUEUE_THRESHOLD 10000 +#define DQCOUNT_INVALID -1 +#define MAX_PROB 0xffffffff +#define PIE_SCALE 8 + +/* parameters used */ +struct pie_params { + psched_time_t target; /* user specified target delay in pschedtime */ + u32 tupdate; /* timer frequency (in jiffies) */ + u32 limit; /* number of packets that can be enqueued */ + u32 alpha; /* alpha and beta are between -4 and 4 */ + u32 beta; /* and are used for shift relative to 1 */ + bool ecn; /* true if ecn is enabled */ + bool bytemode; /* to scale drop early prob based on pkt size */ +}; + +/* variables used */ +struct pie_vars { + u32 prob; /* probability but scaled by u32 limit. */ + psched_time_t burst_time; + psched_time_t qdelay; + psched_time_t qdelay_old; + u64 dq_count; /* measured in bytes */ + psched_time_t dq_tstamp; /* drain rate */ + u32 avg_dq_rate; /* bytes per pschedtime tick,scaled */ + u32 qlen_old; /* in bytes */ +}; + +/* statistics gathering */ +struct pie_stats { + u32 packets_in; /* total number of packets enqueued */ + u32 dropped; /* packets dropped due to pie_action */ + u32 overlimit; /* dropped due to lack of space in queue */ + u32 maxq; /* maximum queue size */ + u32 ecn_mark; /* packets marked with ECN */ +}; + +/* private data for the Qdisc */ +struct pie_sched_data { + struct pie_params params; + struct pie_vars vars; + struct pie_stats stats; + struct timer_list adapt_timer; +}; + +static void pie_params_init(struct pie_params *params) +{ + params->alpha = 2; + params->beta = 20; + params->tupdate = usecs_to_jiffies(30 * USEC_PER_MSEC); /* 30 ms */ + params->limit = 1000; /* default of 1000 packets */ + params->target = PSCHED_NS2TICKS(20 * NSEC_PER_MSEC); /* 20 ms */ + params->ecn = false; + params->bytemode = false; +} + +static void pie_vars_init(struct pie_vars *vars) +{ + vars->dq_count = DQCOUNT_INVALID; + vars->avg_dq_rate = 0; + /* default of 100 ms in pschedtime */ + vars->burst_time = PSCHED_NS2TICKS(100 * NSEC_PER_MSEC); +} + +static bool drop_early(struct Qdisc *sch, u32 packet_size) +{ + struct pie_sched_data *q = qdisc_priv(sch); + u32 rnd; + u32 local_prob = q->vars.prob; + u32 mtu = psched_mtu(qdisc_dev(sch)); + + /* If there is still burst allowance left skip random early drop */ + if (q->vars.burst_time > 0) + return false; + + /* If current delay is less than half of target, and + * if drop prob is low already, disable early_drop + */ + if ((q->vars.qdelay < q->params.target / 2) + && (q->vars.prob < MAX_PROB / 5)) + return false; + + /* If we have fewer than 2 mtu-sized packets, disable drop_early, + * similar to min_th in RED + */ + if (sch->qstats.backlog < 2 * mtu) + return false; + + /* If bytemode is turned on, use packet size to compute new + * probablity. Smaller packets will have lower drop prob in this case + */ + if (q->params.bytemode && packet_size <= mtu) + local_prob = (local_prob / mtu) * packet_size; + else + local_prob = q->vars.prob; + + rnd = net_random(); + if (rnd < local_prob) + return true; + + return false; +} + +static int pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch) +{ + struct pie_sched_data *q = qdisc_priv(sch); + bool enqueue = false; + + if (unlikely(qdisc_qlen(sch) >= sch->limit)) { + q->stats.overlimit++; + goto out; + } + + if (!drop_early(sch, skb->len)) { + enqueue = true; + } else if (q->params.ecn && (q->vars.prob <= MAX_PROB / 10) && + INET_ECN_set_ce(skb)) { + /* If packet is ecn capable, mark it if drop probability + * is lower than 10%, else drop it. + */ + q->stats.ecn_mark++; + enqueue = true; + } + + /* we can enqueue the packet */ + if (enqueue) { + q->stats.packets_in++; + if (qdisc_qlen(sch) > q->stats.maxq) + q->stats.maxq = qdisc_qlen(sch); + + return qdisc_enqueue_tail(skb, sch); + } + +out: + q->stats.dropped++; + return qdisc_drop(skb, sch); +} + +static const struct nla_policy pie_policy[TCA_PIE_MAX + 1] = { + [TCA_PIE_TARGET] = {.type = NLA_U32}, + [TCA_PIE_LIMIT] = {.type = NLA_U32}, + [TCA_PIE_TUPDATE] = {.type = NLA_U32}, + [TCA_PIE_ALPHA] = {.type = NLA_U32}, + [TCA_PIE_BETA] = {.type = NLA_U32}, + [TCA_PIE_ECN] = {.type = NLA_U32}, + [TCA_PIE_BYTEMODE] = {.type = NLA_U32}, +}; + +static int pie_change(struct Qdisc *sch, struct nlattr *opt) +{ + struct pie_sched_data *q = qdisc_priv(sch); + struct nlattr *tb[TCA_PIE_MAX + 1]; + unsigned int qlen; + int err; + + if (!opt) + return -EINVAL; + + err = nla_parse_nested(tb, TCA_PIE_MAX, opt, pie_policy); + if (err < 0) + return err; + + sch_tree_lock(sch); + + /* convert from microseconds to pschedtime */ + if (tb[TCA_PIE_TARGET]) { + /* target is in us */ + u32 target = nla_get_u32(tb[TCA_PIE_TARGET]); + + /* convert to pschedtime */ + q->params.target = PSCHED_NS2TICKS((u64)target * NSEC_PER_USEC); + } + + /* tupdate is in jiffies */ + if (tb[TCA_PIE_TUPDATE]) + q->params.tupdate = usecs_to_jiffies(nla_get_u32(tb[TCA_PIE_TUPDATE])); + + if (tb[TCA_PIE_LIMIT]) { + u32 limit = nla_get_u32(tb[TCA_PIE_LIMIT]); + + q->params.limit = limit; + sch->limit = limit; + } + + if (tb[TCA_PIE_ALPHA]) + q->params.alpha = nla_get_u32(tb[TCA_PIE_ALPHA]); + + if (tb[TCA_PIE_BETA]) + q->params.beta = nla_get_u32(tb[TCA_PIE_BETA]); + + if (tb[TCA_PIE_ECN]) + q->params.ecn = nla_get_u32(tb[TCA_PIE_ECN]); + + if (tb[TCA_PIE_BYTEMODE]) + q->params.bytemode = nla_get_u32(tb[TCA_PIE_BYTEMODE]); + + /* Drop excess packets if new limit is lower */ + 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 void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb) +{ + + struct pie_sched_data *q = qdisc_priv(sch); + int qlen = sch->qstats.backlog; /* current queue size in bytes */ + + /* If current queue is about 10 packets or more and dq_count is unset + * we have enough packets to calculate the drain rate. Save + * current time as dq_tstamp and start measurement cycle. + */ + if (qlen >= QUEUE_THRESHOLD && q->vars.dq_count == DQCOUNT_INVALID) { + q->vars.dq_tstamp = psched_get_time(); + q->vars.dq_count = 0; + } + + /* Calculate the average drain rate from this value. If queue length + * has receded to a small value viz., <= QUEUE_THRESHOLD bytes,reset + * the dq_count to -1 as we don't have enough packets to calculate the + * drain rate anymore The following if block is entered only when we + * have a substantial queue built up (QUEUE_THRESHOLD bytes or more) + * and we calculate the drain rate for the threshold here. dq_count is + * in bytes, time difference in psched_time, hence rate is in + * bytes/psched_time. + */ + if (q->vars.dq_count != DQCOUNT_INVALID) { + q->vars.dq_count += skb->len; + + if (q->vars.dq_count >= QUEUE_THRESHOLD) { + psched_time_t now = psched_get_time(); + u32 dtime = now - q->vars.dq_tstamp; + u32 count = q->vars.dq_count << PIE_SCALE; + + if (dtime == 0) + return; + + count = count / dtime; + + if (q->vars.avg_dq_rate == 0) + q->vars.avg_dq_rate = count; + else + q->vars.avg_dq_rate = + (q->vars.avg_dq_rate - + (q->vars.avg_dq_rate >> 3)) + (count >> 3); + + /* If the queue has receded below the threshold, we hold + * on to the last drain rate calculated, else we reset + * dq_count to 0 to re-enter the if block when the next + * packet is dequeued + */ + if (qlen < QUEUE_THRESHOLD) + q->vars.dq_count = DQCOUNT_INVALID; + else { + q->vars.dq_count = 0; + q->vars.dq_tstamp = psched_get_time(); + } + + if (q->vars.burst_time > 0) { + if (q->vars.burst_time > dtime) + q->vars.burst_time -= dtime; + else + q->vars.burst_time = 0; + } + } + } +} + +static void calculate_probability(struct Qdisc *sch) +{ + struct pie_sched_data *q = qdisc_priv(sch); + u32 qlen = sch->qstats.backlog; /* queue size in bytes */ + psched_time_t qdelay = 0; /* in pschedtime */ + psched_time_t qdelay_old = q->vars.qdelay; /* in pschedtime */ + s32 delta = 0; /* determines the change in probability */ + u32 oldprob; + u32 alpha, beta; + bool update_prob = true; + + q->vars.qdelay_old = q->vars.qdelay; + + if (q->vars.avg_dq_rate > 0) + qdelay = (qlen << PIE_SCALE) / q->vars.avg_dq_rate; + else + qdelay = 0; + + /* If qdelay is zero and qlen is not, it means qlen is very small, less + * than dequeue_rate, so we do not update probabilty in this round + */ + if (qdelay == 0 && qlen != 0) + update_prob = false; + + /* Add ranges for alpha and beta, more aggressive for high dropping + * mode and gentle steps for light dropping mode + * In light dropping mode, take gentle steps; in medium dropping mode, + * take medium steps; in high dropping mode, take big steps. + */ + if (q->vars.prob < MAX_PROB / 100) { + alpha = + (q->params.alpha * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 7; + beta = + (q->params.beta * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 7; + } else if (q->vars.prob < MAX_PROB / 10) { + alpha = + (q->params.alpha * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 5; + beta = + (q->params.beta * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 5; + } else { + alpha = + (q->params.alpha * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4; + beta = + (q->params.beta * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4; + } + + /* alpha and beta should be between 0 and 32, in multiples of 1/16 */ + delta += alpha * ((qdelay - q->params.target)); + delta += beta * ((qdelay - qdelay_old)); + + oldprob = q->vars.prob; + + /* to ensure we increase probability in steps of no more than 2% */ + if (delta > (s32) (MAX_PROB / (100 / 2)) && + q->vars.prob >= MAX_PROB / 10) + delta = (MAX_PROB / 100) * 2; + + /* Non-linear drop: + * Tune drop probability to increase quickly for high delays(>= 250ms) + * 250ms is derived through experiments and provides error protection + */ + + if (qdelay > (PSCHED_NS2TICKS(250 * NSEC_PER_MSEC))) + delta += MAX_PROB / (100 / 2); + + q->vars.prob += delta; + + if (delta > 0) { + /* prevent overflow */ + if (q->vars.prob < oldprob) { + q->vars.prob = MAX_PROB; + /* Prevent normalization error. If probability is at + * maximum value already, we normalize it here, and + * skip the check to do a non-linear drop in the next + * section. + */ + update_prob = false; + } + } else { + /* prevent underflow */ + if (q->vars.prob > oldprob) + q->vars.prob = 0; + } + + /* Non-linear drop in probability: Reduce drop probability quickly if + * delay is 0 for 2 consecutive Tupdate periods. + */ + + if ((qdelay == 0) && (qdelay_old == 0) && update_prob) + q->vars.prob = (q->vars.prob * 98) / 100; + + q->vars.qdelay = qdelay; + q->vars.qlen_old = qlen; + + /* We restart the measurement cycle if the following conditions are met + * 1. If the delay has been low for 2 consecutive Tupdate periods + * 2. Calculated drop probability is zero + * 3. We have atleast one estimate for the avg_dq_rate ie., + * is a non-zero value + */ + if ((q->vars.qdelay < q->params.target / 2) && + (q->vars.qdelay_old < q->params.target / 2) && + (q->vars.prob == 0) && + (q->vars.avg_dq_rate > 0)) + pie_vars_init(&q->vars); +} + +static void pie_timer(unsigned long arg) +{ + struct Qdisc *sch = (struct Qdisc *)arg; + struct pie_sched_data *q = qdisc_priv(sch); + spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch)); + + spin_lock(root_lock); + calculate_probability(sch); + + /* reset the timer to fire after 'tupdate'. tupdate is in jiffies. */ + if (q->params.tupdate) + mod_timer(&q->adapt_timer, jiffies + q->params.tupdate); + spin_unlock(root_lock); + +} + +static int pie_init(struct Qdisc *sch, struct nlattr *opt) +{ + struct pie_sched_data *q = qdisc_priv(sch); + + pie_params_init(&q->params); + pie_vars_init(&q->vars); + sch->limit = q->params.limit; + + setup_timer(&q->adapt_timer, pie_timer, (unsigned long)sch); + mod_timer(&q->adapt_timer, jiffies + HZ / 2); + + if (opt) { + int err = pie_change(sch, opt); + + if (err) + return err; + } + + return 0; +} + +static int pie_dump(struct Qdisc *sch, struct sk_buff *skb) +{ + struct pie_sched_data *q = qdisc_priv(sch); + struct nlattr *opts; + + opts = nla_nest_start(skb, TCA_OPTIONS); + if (opts == NULL) + goto nla_put_failure; + + /* convert target from pschedtime to us */ + if (nla_put_u32(skb, TCA_PIE_TARGET, + ((u32) PSCHED_TICKS2NS(q->params.target)) / + NSEC_PER_USEC) || + nla_put_u32(skb, TCA_PIE_LIMIT, sch->limit) || + nla_put_u32(skb, TCA_PIE_TUPDATE, jiffies_to_usecs(q->params.tupdate)) || + nla_put_u32(skb, TCA_PIE_ALPHA, q->params.alpha) || + nla_put_u32(skb, TCA_PIE_BETA, q->params.beta) || + nla_put_u32(skb, TCA_PIE_ECN, q->params.ecn) || + nla_put_u32(skb, TCA_PIE_BYTEMODE, q->params.bytemode)) + goto nla_put_failure; + + return nla_nest_end(skb, opts); + +nla_put_failure: + nla_nest_cancel(skb, opts); + return -1; + +} + +static int pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d) +{ + struct pie_sched_data *q = qdisc_priv(sch); + struct tc_pie_xstats st = { + .prob = q->vars.prob, + .delay = ((u32) PSCHED_TICKS2NS(q->vars.qdelay)) / + NSEC_PER_USEC, + /* unscale and return dq_rate in bytes per sec */ + .avg_dq_rate = q->vars.avg_dq_rate * + (PSCHED_TICKS_PER_SEC) >> PIE_SCALE, + .packets_in = q->stats.packets_in, + .overlimit = q->stats.overlimit, + .maxq = q->stats.maxq, + .dropped = q->stats.dropped, + .ecn_mark = q->stats.ecn_mark, + }; + + return gnet_stats_copy_app(d, &st, sizeof(st)); +} + +static struct sk_buff *pie_qdisc_dequeue(struct Qdisc *sch) +{ + struct sk_buff *skb; + skb = __qdisc_dequeue_head(sch, &sch->q); + + if (!skb) + return NULL; + + pie_process_dequeue(sch, skb); + return skb; +} + +static void pie_reset(struct Qdisc *sch) +{ + struct pie_sched_data *q = qdisc_priv(sch); + qdisc_reset_queue(sch); + pie_vars_init(&q->vars); +} + +static void pie_destroy(struct Qdisc *sch) +{ + struct pie_sched_data *q = qdisc_priv(sch); + q->params.tupdate = 0; + del_timer_sync(&q->adapt_timer); +} + +static struct Qdisc_ops pie_qdisc_ops __read_mostly = { + .id = "pie", + .priv_size = sizeof(struct pie_sched_data), + .enqueue = pie_qdisc_enqueue, + .dequeue = pie_qdisc_dequeue, + .peek = qdisc_peek_dequeued, + .init = pie_init, + .destroy = pie_destroy, + .reset = pie_reset, + .change = pie_change, + .dump = pie_dump, + .dump_stats = pie_dump_stats, + .owner = THIS_MODULE, +}; + +static int __init pie_module_init(void) +{ + return register_qdisc(&pie_qdisc_ops); +} + +static void __exit pie_module_exit(void) +{ + unregister_qdisc(&pie_qdisc_ops); +} + +module_init(pie_module_init); +module_exit(pie_module_exit); + +MODULE_DESCRIPTION("Proportional Integral controller Enhanced (PIE) scheduler"); +MODULE_AUTHOR("Vijay Subramanian"); +MODULE_AUTHOR("Mythili Prabhu"); +MODULE_LICENSE("GPL"); |