diff options
author | Eric Dumazet <edumazet@google.com> | 2016-06-06 09:37:16 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2016-06-07 16:37:14 -0700 |
commit | edb09eb17ed89eaa82a52dd306beac93e292b485 (patch) | |
tree | 1f241506d6b781b65d1033925f1c1ce6a39c3394 /net/sched | |
parent | f9eb8aea2a1e12fc2f584d1627deeb957435a801 (diff) | |
download | op-kernel-dev-edb09eb17ed89eaa82a52dd306beac93e292b485.zip op-kernel-dev-edb09eb17ed89eaa82a52dd306beac93e292b485.tar.gz |
net: sched: do not acquire qdisc spinlock in qdisc/class stats dump
Large tc dumps (tc -s {qdisc|class} sh dev ethX) done by Google BwE host
agent [1] are problematic at scale :
For each qdisc/class found in the dump, we currently lock the root qdisc
spinlock in order to get stats. Sampling stats every 5 seconds from
thousands of HTB classes is a challenge when the root qdisc spinlock is
under high pressure. Not only the dumps take time, they also slow
down the fast path (queue/dequeue packets) by 10 % to 20 % in some cases.
An audit of existing qdiscs showed that sch_fq_codel is the only qdisc
that might need the qdisc lock in fq_codel_dump_stats() and
fq_codel_dump_class_stats()
In v2 of this patch, I now use the Qdisc running seqcount to provide
consistent reads of packets/bytes counters, regardless of 32/64 bit arches.
I also changed rate estimators to use the same infrastructure
so that they no longer need to lock root qdisc lock.
[1]
http://static.googleusercontent.com/media/research.google.com/en//pubs/archive/43838.pdf
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kevin Athey <kda@google.com>
Cc: Xiaotian Pei <xiaotian@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched')
-rw-r--r-- | net/sched/act_api.c | 4 | ||||
-rw-r--r-- | net/sched/act_police.c | 3 | ||||
-rw-r--r-- | net/sched/sch_api.c | 21 | ||||
-rw-r--r-- | net/sched/sch_atm.c | 3 | ||||
-rw-r--r-- | net/sched/sch_cbq.c | 9 | ||||
-rw-r--r-- | net/sched/sch_drr.c | 9 | ||||
-rw-r--r-- | net/sched/sch_fq_codel.c | 15 | ||||
-rw-r--r-- | net/sched/sch_hfsc.c | 10 | ||||
-rw-r--r-- | net/sched/sch_htb.c | 11 | ||||
-rw-r--r-- | net/sched/sch_mq.c | 2 | ||||
-rw-r--r-- | net/sched/sch_mqprio.c | 11 | ||||
-rw-r--r-- | net/sched/sch_multiq.c | 3 | ||||
-rw-r--r-- | net/sched/sch_prio.c | 3 | ||||
-rw-r--r-- | net/sched/sch_qfq.c | 9 |
14 files changed, 69 insertions, 44 deletions
diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 719bc2e..b6db56e 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -287,7 +287,7 @@ err2: if (est) { err = gen_new_estimator(&p->tcfc_bstats, p->cpu_bstats, &p->tcfc_rate_est, - &p->tcfc_lock, est); + &p->tcfc_lock, NULL, est); if (err) { free_percpu(p->cpu_qstats); goto err2; @@ -671,7 +671,7 @@ int tcf_action_copy_stats(struct sk_buff *skb, struct tc_action *a, if (err < 0) goto errout; - if (gnet_stats_copy_basic(&d, p->cpu_bstats, &p->tcfc_bstats) < 0 || + if (gnet_stats_copy_basic(NULL, &d, p->cpu_bstats, &p->tcfc_bstats) < 0 || gnet_stats_copy_rate_est(&d, &p->tcfc_bstats, &p->tcfc_rate_est) < 0 || gnet_stats_copy_queue(&d, p->cpu_qstats, diff --git a/net/sched/act_police.c b/net/sched/act_police.c index 820b116..bcb3114 100644 --- a/net/sched/act_police.c +++ b/net/sched/act_police.c @@ -185,7 +185,8 @@ override: if (est) { err = gen_replace_estimator(&police->tcf_bstats, NULL, &police->tcf_rate_est, - &police->tcf_lock, est); + &police->tcf_lock, + NULL, est); if (err) goto failure_unlock; } else if (tb[TCA_POLICE_AVRATE] && diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c index ddf047d..d4a8bbf 100644 --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -982,7 +982,7 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue, rcu_assign_pointer(sch->stab, stab); } if (tca[TCA_RATE]) { - spinlock_t *root_lock; + seqcount_t *running; err = -EOPNOTSUPP; if (sch->flags & TCQ_F_MQROOT) @@ -991,14 +991,15 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue, if ((sch->parent != TC_H_ROOT) && !(sch->flags & TCQ_F_INGRESS) && (!p || !(p->flags & TCQ_F_MQROOT))) - root_lock = qdisc_root_sleeping_lock(sch); + running = qdisc_root_sleeping_running(sch); else - root_lock = qdisc_lock(sch); + running = &sch->running; err = gen_new_estimator(&sch->bstats, sch->cpu_bstats, &sch->rate_est, - root_lock, + NULL, + running, tca[TCA_RATE]); if (err) goto err_out4; @@ -1061,7 +1062,8 @@ static int qdisc_change(struct Qdisc *sch, struct nlattr **tca) gen_replace_estimator(&sch->bstats, sch->cpu_bstats, &sch->rate_est, - qdisc_root_sleeping_lock(sch), + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); } out: @@ -1369,8 +1371,7 @@ static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid, goto nla_put_failure; if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS, TCA_XSTATS, - qdisc_root_sleeping_lock(q), &d, - TCA_PAD) < 0) + NULL, &d, TCA_PAD) < 0) goto nla_put_failure; if (q->ops->dump_stats && q->ops->dump_stats(q, &d) < 0) @@ -1381,7 +1382,8 @@ static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid, cpu_qstats = q->cpu_qstats; } - if (gnet_stats_copy_basic(&d, cpu_bstats, &q->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(q), + &d, cpu_bstats, &q->bstats) < 0 || gnet_stats_copy_rate_est(&d, &q->bstats, &q->rate_est) < 0 || gnet_stats_copy_queue(&d, cpu_qstats, &q->qstats, qlen) < 0) goto nla_put_failure; @@ -1684,8 +1686,7 @@ static int tc_fill_tclass(struct sk_buff *skb, struct Qdisc *q, goto nla_put_failure; if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS, TCA_XSTATS, - qdisc_root_sleeping_lock(q), &d, - TCA_PAD) < 0) + NULL, &d, TCA_PAD) < 0) goto nla_put_failure; if (cl_ops->dump_stats && cl_ops->dump_stats(q, cl, &d) < 0) diff --git a/net/sched/sch_atm.c b/net/sched/sch_atm.c index 1911af3..34f8f79 100644 --- a/net/sched/sch_atm.c +++ b/net/sched/sch_atm.c @@ -637,7 +637,8 @@ atm_tc_dump_class_stats(struct Qdisc *sch, unsigned long arg, { struct atm_flow_data *flow = (struct atm_flow_data *)arg; - if (gnet_stats_copy_basic(d, NULL, &flow->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), + d, NULL, &flow->bstats) < 0 || gnet_stats_copy_queue(d, NULL, &flow->qstats, flow->q->q.qlen) < 0) return -1; diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c index baafddf..1b8128f 100644 --- a/net/sched/sch_cbq.c +++ b/net/sched/sch_cbq.c @@ -1600,7 +1600,8 @@ cbq_dump_class_stats(struct Qdisc *sch, unsigned long arg, if (cl->undertime != PSCHED_PASTPERFECT) cl->xstats.undertime = cl->undertime - q->now; - if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), + d, NULL, &cl->bstats) < 0 || gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 || gnet_stats_copy_queue(d, NULL, &cl->qstats, cl->q->q.qlen) < 0) return -1; @@ -1755,7 +1756,8 @@ cbq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, struct nlattr **t if (tca[TCA_RATE]) { err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est, - qdisc_root_sleeping_lock(sch), + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); if (err) { qdisc_put_rtab(rtab); @@ -1848,7 +1850,8 @@ cbq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, struct nlattr **t if (tca[TCA_RATE]) { err = gen_new_estimator(&cl->bstats, NULL, &cl->rate_est, - qdisc_root_sleeping_lock(sch), + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); if (err) { kfree(cl); diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c index a63e879..1b7e1a2 100644 --- a/net/sched/sch_drr.c +++ b/net/sched/sch_drr.c @@ -91,7 +91,8 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, if (tca[TCA_RATE]) { err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est, - qdisc_root_sleeping_lock(sch), + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); if (err) return err; @@ -119,7 +120,8 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, if (tca[TCA_RATE]) { err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est, - qdisc_root_sleeping_lock(sch), + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); if (err) { qdisc_destroy(cl->qdisc); @@ -279,7 +281,8 @@ static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg, if (qlen) xstats.deficit = cl->deficit; - if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), + d, NULL, &cl->bstats) < 0 || gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 || gnet_stats_copy_queue(d, NULL, &cl->qdisc->qstats, qlen) < 0) return -1; diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c index 6883a89..1daa542 100644 --- a/net/sched/sch_fq_codel.c +++ b/net/sched/sch_fq_codel.c @@ -566,11 +566,13 @@ static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d) st.qdisc_stats.memory_usage = q->memory_usage; st.qdisc_stats.drop_overmemory = q->drop_overmemory; + sch_tree_lock(sch); list_for_each(pos, &q->new_flows) st.qdisc_stats.new_flows_len++; list_for_each(pos, &q->old_flows) st.qdisc_stats.old_flows_len++; + sch_tree_unlock(sch); return gnet_stats_copy_app(d, &st, sizeof(st)); } @@ -624,7 +626,7 @@ static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl, if (idx < q->flows_cnt) { const struct fq_codel_flow *flow = &q->flows[idx]; - const struct sk_buff *skb = flow->head; + const struct sk_buff *skb; memset(&xstats, 0, sizeof(xstats)); xstats.type = TCA_FQ_CODEL_XSTATS_CLASS; @@ -642,9 +644,14 @@ static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl, codel_time_to_us(delta) : -codel_time_to_us(-delta); } - while (skb) { - qs.qlen++; - skb = skb->next; + if (flow->head) { + sch_tree_lock(sch); + skb = flow->head; + while (skb) { + qs.qlen++; + skb = skb->next; + } + sch_tree_unlock(sch); } qs.backlog = q->backlogs[idx]; qs.drops = flow->dropped; diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c index d783d7c..74813dd 100644 --- a/net/sched/sch_hfsc.c +++ b/net/sched/sch_hfsc.c @@ -1015,11 +1015,10 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid, cur_time = psched_get_time(); if (tca[TCA_RATE]) { - spinlock_t *lock = qdisc_root_sleeping_lock(sch); - err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est, - lock, + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); if (err) return err; @@ -1068,7 +1067,8 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid, if (tca[TCA_RATE]) { err = gen_new_estimator(&cl->bstats, NULL, &cl->rate_est, - qdisc_root_sleeping_lock(sch), + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); if (err) { kfree(cl); @@ -1373,7 +1373,7 @@ hfsc_dump_class_stats(struct Qdisc *sch, unsigned long arg, xstats.work = cl->cl_total; xstats.rtwork = cl->cl_cumul; - if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), d, NULL, &cl->bstats) < 0 || gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 || gnet_stats_copy_queue(d, NULL, &cl->qstats, cl->qdisc->q.qlen) < 0) return -1; diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index d4b4218..2b05764 100644 --- a/net/sched/sch_htb.c +++ b/net/sched/sch_htb.c @@ -1141,7 +1141,8 @@ htb_dump_class_stats(struct Qdisc *sch, unsigned long arg, struct gnet_dump *d) cl->xstats.tokens = PSCHED_NS2TICKS(cl->tokens); cl->xstats.ctokens = PSCHED_NS2TICKS(cl->ctokens); - if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), + d, NULL, &cl->bstats) < 0 || gnet_stats_copy_rate_est(d, NULL, &cl->rate_est) < 0 || gnet_stats_copy_queue(d, NULL, &cl->qstats, qlen) < 0) return -1; @@ -1395,7 +1396,8 @@ static int htb_change_class(struct Qdisc *sch, u32 classid, if (htb_rate_est || tca[TCA_RATE]) { err = gen_new_estimator(&cl->bstats, NULL, &cl->rate_est, - qdisc_root_sleeping_lock(sch), + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE] ? : &est.nla); if (err) { kfree(cl); @@ -1457,11 +1459,10 @@ static int htb_change_class(struct Qdisc *sch, u32 classid, parent->children++; } else { if (tca[TCA_RATE]) { - spinlock_t *lock = qdisc_root_sleeping_lock(sch); - err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est, - lock, + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); if (err) return err; diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c index 56a77b8..b943982 100644 --- a/net/sched/sch_mq.c +++ b/net/sched/sch_mq.c @@ -199,7 +199,7 @@ static int mq_dump_class_stats(struct Qdisc *sch, unsigned long cl, struct netdev_queue *dev_queue = mq_queue_get(sch, cl); sch = dev_queue->qdisc_sleeping; - if (gnet_stats_copy_basic(d, NULL, &sch->bstats) < 0 || + if (gnet_stats_copy_basic(&sch->running, d, NULL, &sch->bstats) < 0 || gnet_stats_copy_queue(d, NULL, &sch->qstats, sch->q.qlen) < 0) return -1; return 0; diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c index b8002ce..549c663 100644 --- a/net/sched/sch_mqprio.c +++ b/net/sched/sch_mqprio.c @@ -342,7 +342,8 @@ static int mqprio_dump_class_stats(struct Qdisc *sch, unsigned long cl, * hold here is the look on dev_queue->qdisc_sleeping * also acquired below. */ - spin_unlock_bh(d->lock); + if (d->lock) + spin_unlock_bh(d->lock); for (i = tc.offset; i < tc.offset + tc.count; i++) { struct netdev_queue *q = netdev_get_tx_queue(dev, i); @@ -359,15 +360,17 @@ static int mqprio_dump_class_stats(struct Qdisc *sch, unsigned long cl, spin_unlock_bh(qdisc_lock(qdisc)); } /* Reclaim root sleeping lock before completing stats */ - spin_lock_bh(d->lock); - if (gnet_stats_copy_basic(d, NULL, &bstats) < 0 || + if (d->lock) + spin_lock_bh(d->lock); + if (gnet_stats_copy_basic(NULL, d, NULL, &bstats) < 0 || gnet_stats_copy_queue(d, NULL, &qstats, qlen) < 0) return -1; } else { struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl); sch = dev_queue->qdisc_sleeping; - if (gnet_stats_copy_basic(d, NULL, &sch->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), + d, NULL, &sch->bstats) < 0 || gnet_stats_copy_queue(d, NULL, &sch->qstats, sch->q.qlen) < 0) return -1; diff --git a/net/sched/sch_multiq.c b/net/sched/sch_multiq.c index bcdd54b..21e69d2 100644 --- a/net/sched/sch_multiq.c +++ b/net/sched/sch_multiq.c @@ -356,7 +356,8 @@ static int multiq_dump_class_stats(struct Qdisc *sch, unsigned long cl, struct Qdisc *cl_q; cl_q = q->queues[cl - 1]; - if (gnet_stats_copy_basic(d, NULL, &cl_q->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), + d, NULL, &cl_q->bstats) < 0 || gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0) return -1; diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c index fee1b15..06eca70 100644 --- a/net/sched/sch_prio.c +++ b/net/sched/sch_prio.c @@ -319,7 +319,8 @@ static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl, struct Qdisc *cl_q; cl_q = q->queues[cl - 1]; - if (gnet_stats_copy_basic(d, NULL, &cl_q->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), + d, NULL, &cl_q->bstats) < 0 || gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0) return -1; diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index 8d2d8d9..85d4197 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -460,7 +460,8 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, if (tca[TCA_RATE]) { err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est, - qdisc_root_sleeping_lock(sch), + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); if (err) return err; @@ -486,7 +487,8 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, if (tca[TCA_RATE]) { err = gen_new_estimator(&cl->bstats, NULL, &cl->rate_est, - qdisc_root_sleeping_lock(sch), + NULL, + qdisc_root_sleeping_running(sch), tca[TCA_RATE]); if (err) goto destroy_class; @@ -663,7 +665,8 @@ static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg, xstats.weight = cl->agg->class_weight; xstats.lmax = cl->agg->lmax; - if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 || + if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), + d, NULL, &cl->bstats) < 0 || gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 || gnet_stats_copy_queue(d, NULL, &cl->qdisc->qstats, cl->qdisc->q.qlen) < 0) |