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ipv4: reduce percpu needs for icmpmsg mibs

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Reading /proc/net/snmp on a machine with a lot of cpus is very expensive
(can be ~88000 us).

This is because ICMPMSG MIB uses 4096 bytes per cpu, and folding values
for all possible cpus can read 16 Mbytes of memory.

ICMP messages are not considered as fast path on a typical server, and
eventually few cpus handle them anyway. We can afford an atomic
operation instead of using percpu data.

This saves 4096 bytes per cpu and per network namespace.

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 2011-11-08 13:04:43 +00:00 • committed by David S. Miller
parent e56c57d0d3
commit acb32ba3de
5 changed files with 12 additions and 13 deletions
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8
net/ipv4/af_inet.c
View file

@ -1572,9 +1572,9 @@ static __net_init int ipv4_mib_init_net(struct net *net)
sizeof(struct icmp_mib),
__alignof__(struct icmp_mib)) < 0)
goto err_icmp_mib;
if (snmp_mib_init((void __percpu **)net->mib.icmpmsg_statistics,
sizeof(struct icmpmsg_mib),
__alignof__(struct icmpmsg_mib)) < 0)
net->mib.icmpmsg_statistics = kzalloc(sizeof(struct icmpmsg_mib),
GFP_KERNEL);
if (!net->mib.icmpmsg_statistics)
goto err_icmpmsg_mib;
tcp_mib_init(net);
@ -1598,7 +1598,7 @@ err_tcp_mib:
static __net_exit void ipv4_mib_exit_net(struct net *net)
{
snmp_mib_free((void __percpu **)net->mib.icmpmsg_statistics);
kfree(net->mib.icmpmsg_statistics);
snmp_mib_free((void __percpu **)net->mib.icmp_statistics);
snmp_mib_free((void __percpu **)net->mib.udplite_statistics);
snmp_mib_free((void __percpu **)net->mib.udp_statistics);