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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-10-13 08:22:03 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-10-16 11:13:23 -0700 |
| commit | 10da66f7552b3c7966c2f4f1f72009fb0b5539ec (patch) | |
| tree | 517c39912a0aea9d4da3c3915c78e832dfbba855 | |
| parent | 874ffa8f72444d6253d2669fed304875c128f86b (diff) | |
| download | op-kernel-dev-10da66f7552b3c7966c2f4f1f72009fb0b5539ec.zip op-kernel-dev-10da66f7552b3c7966c2f4f1f72009fb0b5539ec.tar.gz | |
fib: avoid false sharing on fib_table_hash
While doing profile analysis, I found fib_hash_table was sometime in a
cache line shared by a possibly often written kernel structure.
(CONFIG_IP_ROUTE_MULTIPATH || !CONFIG_IPV6_MULTIPLE_TABLES)
It's hard to detect because not easily reproductible.
Make sure we allocate a full cache line to keep this shared in all cpus
caches.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/fib_frontend.c | 11 | ||||
| -rw-r--r-- | net/ipv6/ip6_fib.c | 9 |
2 files changed, 11 insertions, 9 deletions
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 919f2ad..3df057e 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -1016,16 +1016,15 @@ static struct notifier_block fib_netdev_notifier = { static int __net_init ip_fib_net_init(struct net *net) { int err; - unsigned int i; + size_t size = sizeof(struct hlist_head) * FIB_TABLE_HASHSZ; + + /* Avoid false sharing : Use at least a full cache line */ + size = max_t(size_t, size, L1_CACHE_BYTES); - net->ipv4.fib_table_hash = kzalloc( - sizeof(struct hlist_head)*FIB_TABLE_HASHSZ, GFP_KERNEL); + net->ipv4.fib_table_hash = kzalloc(size, GFP_KERNEL); if (net->ipv4.fib_table_hash == NULL) return -ENOMEM; - for (i = 0; i < FIB_TABLE_HASHSZ; i++) - INIT_HLIST_HEAD(&net->ipv4.fib_table_hash[i]); - err = fib4_rules_init(net); if (err < 0) goto fail; diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index b6a5859..de38211 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -1500,15 +1500,18 @@ static void fib6_gc_timer_cb(unsigned long arg) static int __net_init fib6_net_init(struct net *net) { + size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ; + setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net); net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL); if (!net->ipv6.rt6_stats) goto out_timer; - net->ipv6.fib_table_hash = kcalloc(FIB6_TABLE_HASHSZ, - sizeof(*net->ipv6.fib_table_hash), - GFP_KERNEL); + /* Avoid false sharing : Use at least a full cache line */ + size = max_t(size_t, size, L1_CACHE_BYTES); + + net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL); if (!net->ipv6.fib_table_hash) goto out_rt6_stats; |
