From efbf78973978b0d25af59bc26c8013a942af6e64 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Mon, 4 Dec 2017 10:48:18 -0800 Subject: net_sched: get rid of rcu_barrier() in tcf_block_put_ext() Both Eric and Paolo noticed the rcu_barrier() we use in tcf_block_put_ext() could be a performance bottleneck when we have a lot of tc classes. Paolo provided the following to demonstrate the issue: tc qdisc add dev lo root htb for I in `seq 1 1000`; do tc class add dev lo parent 1: classid 1:$I htb rate 100kbit tc qdisc add dev lo parent 1:$I handle $((I + 1)): htb for J in `seq 1 10`; do tc filter add dev lo parent $((I + 1)): u32 match ip src 1.1.1.$J done done time tc qdisc del dev root real 0m54.764s user 0m0.023s sys 0m0.000s The rcu_barrier() there is to ensure we free the block after all chains are gone, that is, to queue tcf_block_put_final() at the tail of workqueue. We can achieve this ordering requirement by refcnt'ing tcf block instead, that is, the tcf block is freed only when the last chain in this block is gone. This also simplifies the code. Paolo reported after this patch we get: real 0m0.017s user 0m0.000s sys 0m0.017s Tested-by: Paolo Abeni Cc: Eric Dumazet Cc: Jiri Pirko Cc: Jamal Hadi Salim Signed-off-by: Cong Wang Signed-off-by: David S. Miller --- include/net/sch_generic.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include') diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 65d0d25f2648..02e7ad8b8dad 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -278,7 +278,6 @@ struct tcf_block { struct net *net; struct Qdisc *q; struct list_head cb_list; - struct work_struct work; }; static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz) -- cgit v1.2.3