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net dst: use a percpu_counter to track entries

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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 <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2010-10-08 06:37:34 +00:00
committed by David S. Miller
parent 0ed8ddf404
commit fc66f95c68
8 changed files with 100 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
net/bridge/br_netfilter.c
View File

@@ -106,7 +106,6 @@ static struct dst_ops fake_dst_ops = {
.family = AF_INET,
.protocol = cpu_to_be16(ETH_P_IP),
.update_pmtu = fake_update_pmtu,
.entries = ATOMIC_INIT(0),
};
/*
@@ -1003,15 +1002,22 @@ int __init br_netfilter_init(void)
{
int ret;
ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
ret = dst_entries_init(&fake_dst_ops);
if (ret < 0)
return ret;
ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
if (ret < 0) {
dst_entries_destroy(&fake_dst_ops);
return ret;
}
#ifdef CONFIG_SYSCTL
brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
if (brnf_sysctl_header == NULL) {
printk(KERN_WARNING
"br_netfilter: can't register to sysctl.\n");
nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
dst_entries_destroy(&fake_dst_ops);
return -ENOMEM;
}
#endif
@@ -1025,4 +1031,5 @@ void br_netfilter_fini(void)
#ifdef CONFIG_SYSCTL
unregister_sysctl_table(brnf_sysctl_header);
#endif
dst_entries_destroy(&fake_dst_ops);
}