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 --- net/ipv4/route.c | 36 ++++++++++++++++++++++-------------- net/ipv4/xfrm4_policy.c | 4 ++-- 2 files changed, 24 insertions(+), 16 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 3888f6ba0a5c..0755aa4af86c 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -159,7 +159,6 @@ static struct dst_ops ipv4_dst_ops = { .link_failure = ipv4_link_failure, .update_pmtu = ip_rt_update_pmtu, .local_out = __ip_local_out, - .entries = ATOMIC_INIT(0), }; #define ECN_OR_COST(class) TC_PRIO_##class @@ -466,7 +465,7 @@ static int rt_cpu_seq_show(struct seq_file *seq, void *v) seq_printf(seq,"%08x %08x %08x %08x %08x %08x %08x %08x " " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n", - atomic_read(&ipv4_dst_ops.entries), + dst_entries_get_slow(&ipv4_dst_ops), st->in_hit, st->in_slow_tot, st->in_slow_mc, @@ -945,6 +944,7 @@ static int rt_garbage_collect(struct dst_ops *ops) struct rtable *rth, **rthp; unsigned long now = jiffies; int goal; + int entries = dst_entries_get_fast(&ipv4_dst_ops); /* * Garbage collection is pretty expensive, @@ -954,28 +954,28 @@ static int rt_garbage_collect(struct dst_ops *ops) RT_CACHE_STAT_INC(gc_total); if (now - last_gc < ip_rt_gc_min_interval && - atomic_read(&ipv4_dst_ops.entries) < ip_rt_max_size) { + entries < ip_rt_max_size) { RT_CACHE_STAT_INC(gc_ignored); goto out; } + entries = dst_entries_get_slow(&ipv4_dst_ops); /* Calculate number of entries, which we want to expire now. */ - goal = atomic_read(&ipv4_dst_ops.entries) - - (ip_rt_gc_elasticity << rt_hash_log); + goal = entries - (ip_rt_gc_elasticity << rt_hash_log); if (goal <= 0) { if (equilibrium < ipv4_dst_ops.gc_thresh) equilibrium = ipv4_dst_ops.gc_thresh; - goal = atomic_read(&ipv4_dst_ops.entries) - equilibrium; + goal = entries - equilibrium; if (goal > 0) { equilibrium += min_t(unsigned int, goal >> 1, rt_hash_mask + 1); - goal = atomic_read(&ipv4_dst_ops.entries) - equilibrium; + goal = entries - equilibrium; } } else { /* We are in dangerous area. Try to reduce cache really * aggressively. */ goal = max_t(unsigned int, goal >> 1, rt_hash_mask + 1); - equilibrium = atomic_read(&ipv4_dst_ops.entries) - goal; + equilibrium = entries - goal; } if (now - last_gc >= ip_rt_gc_min_interval) @@ -1032,14 +1032,16 @@ static int rt_garbage_collect(struct dst_ops *ops) expire >>= 1; #if RT_CACHE_DEBUG >= 2 printk(KERN_DEBUG "expire>> %u %d %d %d\n", expire, - atomic_read(&ipv4_dst_ops.entries), goal, i); + dst_entries_get_fast(&ipv4_dst_ops), goal, i); #endif - if (atomic_read(&ipv4_dst_ops.entries) < ip_rt_max_size) + if (dst_entries_get_fast(&ipv4_dst_ops) < ip_rt_max_size) goto out; } while (!in_softirq() && time_before_eq(jiffies, now)); - if (atomic_read(&ipv4_dst_ops.entries) < ip_rt_max_size) + if (dst_entries_get_fast(&ipv4_dst_ops) < ip_rt_max_size) + goto out; + if (dst_entries_get_slow(&ipv4_dst_ops) < ip_rt_max_size) goto out; if (net_ratelimit()) printk(KERN_WARNING "dst cache overflow\n"); @@ -1049,11 +1051,12 @@ static int rt_garbage_collect(struct dst_ops *ops) work_done: expire += ip_rt_gc_min_interval; if (expire > ip_rt_gc_timeout || - atomic_read(&ipv4_dst_ops.entries) < ipv4_dst_ops.gc_thresh) + dst_entries_get_fast(&ipv4_dst_ops) < ipv4_dst_ops.gc_thresh || + dst_entries_get_slow(&ipv4_dst_ops) < ipv4_dst_ops.gc_thresh) expire = ip_rt_gc_timeout; #if RT_CACHE_DEBUG >= 2 printk(KERN_DEBUG "expire++ %u %d %d %d\n", expire, - atomic_read(&ipv4_dst_ops.entries), goal, rover); + dst_entries_get_fast(&ipv4_dst_ops), goal, rover); #endif out: return 0; } @@ -2717,7 +2720,6 @@ static struct dst_ops ipv4_dst_blackhole_ops = { .destroy = ipv4_dst_destroy, .check = ipv4_blackhole_dst_check, .update_pmtu = ipv4_rt_blackhole_update_pmtu, - .entries = ATOMIC_INIT(0), }; @@ -3287,6 +3289,12 @@ int __init ip_rt_init(void) ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep; + if (dst_entries_init(&ipv4_dst_ops) < 0) + panic("IP: failed to allocate ipv4_dst_ops counter\n"); + + if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0) + panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n"); + rt_hash_table = (struct rt_hash_bucket *) alloc_large_system_hash("IP route cache", sizeof(struct rt_hash_bucket), diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c index a580349f0b8a..4464f3bff6a7 100644 --- a/net/ipv4/xfrm4_policy.c +++ b/net/ipv4/xfrm4_policy.c @@ -174,7 +174,7 @@ static inline int xfrm4_garbage_collect(struct dst_ops *ops) struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops); xfrm4_policy_afinfo.garbage_collect(net); - return (atomic_read(&ops->entries) > ops->gc_thresh * 2); + return (dst_entries_get_slow(ops) > ops->gc_thresh * 2); } static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu) @@ -232,7 +232,6 @@ static struct dst_ops xfrm4_dst_ops = { .ifdown = xfrm4_dst_ifdown, .local_out = __ip_local_out, .gc_thresh = 1024, - .entries = ATOMIC_INIT(0), }; static struct xfrm_policy_afinfo xfrm4_policy_afinfo = { @@ -288,6 +287,7 @@ void __init xfrm4_init(int rt_max_size) * and start cleaning when were 1/2 full */ xfrm4_dst_ops.gc_thresh = rt_max_size/2; + dst_entries_init(&xfrm4_dst_ops); xfrm4_state_init(); xfrm4_policy_init(); -- cgit v1.2.3