From fc66f95c68b6d4535a0ea2ea15d5cf626e310956 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 8 Oct 2010 06:37:34 +0000 Subject: net dst: use a percpu_counter to track entries struct dst_ops tracks number of allocated dst in an atomic_t field, subject to high cache line contention in stress workload. Switch to a percpu_counter, to reduce number of time we need to dirty a central location. Place it on a separate cache line to avoid dirtying read only fields. Stress test : (Sending 160.000.000 UDP frames, IP route cache disabled, dual E5540 @2.53GHz, 32bit kernel, FIB_TRIE, SLUB/NUMA) Before: real 0m51.179s user 0m15.329s sys 10m15.942s After: real 0m45.570s user 0m15.525s sys 9m56.669s With a small reordering of struct neighbour fields, subject of a following patch, (to separate refcnt from other read mostly fields) real 0m41.841s user 0m15.261s sys 8m45.949s Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/dst_ops.h | 37 ++++++++++++++++++++++++++++++++++++- 1 file changed, 36 insertions(+), 1 deletion(-) (limited to 'include/net/dst_ops.h') diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h index d1ff9b7e99b8..1fa5306e3e23 100644 --- a/include/net/dst_ops.h +++ b/include/net/dst_ops.h @@ -1,6 +1,7 @@ #ifndef _NET_DST_OPS_H #define _NET_DST_OPS_H #include +#include struct dst_entry; struct kmem_cachep; @@ -22,7 +23,41 @@ struct dst_ops { void (*update_pmtu)(struct dst_entry *dst, u32 mtu); int (*local_out)(struct sk_buff *skb); - atomic_t entries; struct kmem_cache *kmem_cachep; + + struct percpu_counter pcpuc_entries ____cacheline_aligned_in_smp; }; + +static inline int dst_entries_get_fast(struct dst_ops *dst) +{ + return percpu_counter_read_positive(&dst->pcpuc_entries); +} + +static inline int dst_entries_get_slow(struct dst_ops *dst) +{ + int res; + + local_bh_disable(); + res = percpu_counter_sum_positive(&dst->pcpuc_entries); + local_bh_enable(); + return res; +} + +static inline void dst_entries_add(struct dst_ops *dst, int val) +{ + local_bh_disable(); + percpu_counter_add(&dst->pcpuc_entries, val); + local_bh_enable(); +} + +static inline int dst_entries_init(struct dst_ops *dst) +{ + return percpu_counter_init(&dst->pcpuc_entries, 0); +} + +static inline void dst_entries_destroy(struct dst_ops *dst) +{ + percpu_counter_destroy(&dst->pcpuc_entries); +} + #endif -- cgit v1.2.2