From 1c0d32fde5bdf1184bc274f864c09799278a1114 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 4 Dec 2016 09:48:16 -0800 Subject: net_sched: gen_estimator: complete rewrite of rate estimators 1) Old code was hard to maintain, due to complex lock chains. (We probably will be able to remove some kfree_rcu() in callers) 2) Using a single timer to update all estimators does not scale. 3) Code was buggy on 32bit kernel (WRITE_ONCE() on 64bit quantity is not supposed to work well) In this rewrite : - I removed the RB tree that had to be scanned in gen_estimator_active(). qdisc dumps should be much faster. - Each estimator has its own timer. - Estimations are maintained in net_rate_estimator structure, instead of dirtying the qdisc. Minor, but part of the simplification. - Reading the estimator uses RCU and a seqcount to provide proper support for 32bit kernels. - We reduce memory need when estimators are not used, since we store a pointer, instead of the bytes/packets counters. - xt_rateest_mt() no longer has to grab a spinlock. (In the future, xt_rateest_tg() could be switched to per cpu counters) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/act_api.h | 2 +- include/net/gen_stats.h | 17 +++++++++-------- include/net/netfilter/xt_rateest.h | 10 +++++++--- include/net/sch_generic.h | 2 +- 4 files changed, 18 insertions(+), 13 deletions(-) (limited to 'include/net') diff --git a/include/net/act_api.h b/include/net/act_api.h index 9dddf77a69cc..1d716449209e 100644 --- a/include/net/act_api.h +++ b/include/net/act_api.h @@ -36,7 +36,7 @@ struct tc_action { struct tcf_t tcfa_tm; struct gnet_stats_basic_packed tcfa_bstats; struct gnet_stats_queue tcfa_qstats; - struct gnet_stats_rate_est64 tcfa_rate_est; + struct net_rate_estimator __rcu *tcfa_rate_est; spinlock_t tcfa_lock; struct rcu_head tcfa_rcu; struct gnet_stats_basic_cpu __percpu *cpu_bstats; diff --git a/include/net/gen_stats.h b/include/net/gen_stats.h index 231e121cc7d9..8b7aa370e7a4 100644 --- a/include/net/gen_stats.h +++ b/include/net/gen_stats.h @@ -11,6 +11,8 @@ struct gnet_stats_basic_cpu { struct u64_stats_sync syncp; }; +struct net_rate_estimator; + struct gnet_dump { spinlock_t * lock; struct sk_buff * skb; @@ -42,8 +44,7 @@ void __gnet_stats_copy_basic(const seqcount_t *running, struct gnet_stats_basic_cpu __percpu *cpu, struct gnet_stats_basic_packed *b); int gnet_stats_copy_rate_est(struct gnet_dump *d, - const struct gnet_stats_basic_packed *b, - struct gnet_stats_rate_est64 *r); + struct net_rate_estimator __rcu **ptr); int gnet_stats_copy_queue(struct gnet_dump *d, struct gnet_stats_queue __percpu *cpu_q, struct gnet_stats_queue *q, __u32 qlen); @@ -53,16 +54,16 @@ int gnet_stats_finish_copy(struct gnet_dump *d); int gen_new_estimator(struct gnet_stats_basic_packed *bstats, struct gnet_stats_basic_cpu __percpu *cpu_bstats, - struct gnet_stats_rate_est64 *rate_est, + struct net_rate_estimator __rcu **rate_est, spinlock_t *stats_lock, seqcount_t *running, struct nlattr *opt); -void gen_kill_estimator(struct gnet_stats_basic_packed *bstats, - struct gnet_stats_rate_est64 *rate_est); +void gen_kill_estimator(struct net_rate_estimator __rcu **ptr); int gen_replace_estimator(struct gnet_stats_basic_packed *bstats, struct gnet_stats_basic_cpu __percpu *cpu_bstats, - struct gnet_stats_rate_est64 *rate_est, + struct net_rate_estimator __rcu **ptr, spinlock_t *stats_lock, seqcount_t *running, struct nlattr *opt); -bool gen_estimator_active(const struct gnet_stats_basic_packed *bstats, - const struct gnet_stats_rate_est64 *rate_est); +bool gen_estimator_active(struct net_rate_estimator __rcu **ptr); +bool gen_estimator_read(struct net_rate_estimator __rcu **ptr, + struct gnet_stats_rate_est64 *sample); #endif diff --git a/include/net/netfilter/xt_rateest.h b/include/net/netfilter/xt_rateest.h index 79f45e19f31e..130e58361f99 100644 --- a/include/net/netfilter/xt_rateest.h +++ b/include/net/netfilter/xt_rateest.h @@ -1,19 +1,23 @@ #ifndef _XT_RATEEST_H #define _XT_RATEEST_H +#include + struct xt_rateest { /* keep lock and bstats on same cache line to speedup xt_rateest_tg() */ struct gnet_stats_basic_packed bstats; spinlock_t lock; - /* keep rstats and lock on same cache line to speedup xt_rateest_mt() */ - struct gnet_stats_rate_est64 rstats; + /* following fields not accessed in hot path */ + unsigned int refcnt; struct hlist_node list; char name[IFNAMSIZ]; - unsigned int refcnt; struct gnet_estimator params; struct rcu_head rcu; + + /* keep this field far away to speedup xt_rateest_mt() */ + struct net_rate_estimator __rcu *rate_est; }; struct xt_rateest *xt_rateest_lookup(const char *name); diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index e6aa0a249672..498f81b229a4 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -76,7 +76,7 @@ struct Qdisc { struct netdev_queue *dev_queue; - struct gnet_stats_rate_est64 rate_est; + struct net_rate_estimator __rcu *rate_est; struct gnet_stats_basic_cpu __percpu *cpu_bstats; struct gnet_stats_queue __percpu *cpu_qstats; -- cgit v1.2.3