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authorEric Dumazet <eric.dumazet@gmail.com>2011-11-08 17:04:43 +0400
committerDavid S. Miller <davem@davemloft.net>2011-11-10 01:04:20 +0400
commitacb32ba3dee66d58704caeeb8c6ff95f60efdc66 (patch)
treeb5c1d6d5575a7b75c7c816e0809690f58401715c /net/ipv4/proc.c
parente56c57d0d3fdbbdf583d3af96bfb803b8dfa713e (diff)
downloadlinux-acb32ba3dee66d58704caeeb8c6ff95f60efdc66.tar.xz
ipv4: reduce percpu needs for icmpmsg mibs
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>
Diffstat (limited to 'net/ipv4/proc.c')
-rw-r--r--net/ipv4/proc.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 466ea8bb7a4d..961eed4f510a 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -288,7 +288,7 @@ static void icmpmsg_put(struct seq_file *seq)
count = 0;
for (i = 0; i < ICMPMSG_MIB_MAX; i++) {
- val = snmp_fold_field((void __percpu **) net->mib.icmpmsg_statistics, i);
+ val = atomic_long_read(&net->mib.icmpmsg_statistics->mibs[i]);
if (val) {
type[count] = i;
vals[count++] = val;
@@ -307,6 +307,7 @@ static void icmp_put(struct seq_file *seq)
{
int i;
struct net *net = seq->private;
+ atomic_long_t *ptr = net->mib.icmpmsg_statistics->mibs;
seq_puts(seq, "\nIcmp: InMsgs InErrors");
for (i=0; icmpmibmap[i].name != NULL; i++)
@@ -319,15 +320,13 @@ static void icmp_put(struct seq_file *seq)
snmp_fold_field((void __percpu **) net->mib.icmp_statistics, ICMP_MIB_INERRORS));
for (i=0; icmpmibmap[i].name != NULL; i++)
seq_printf(seq, " %lu",
- snmp_fold_field((void __percpu **) net->mib.icmpmsg_statistics,
- icmpmibmap[i].index));
+ atomic_long_read(ptr + icmpmibmap[i].index));
seq_printf(seq, " %lu %lu",
snmp_fold_field((void __percpu **) net->mib.icmp_statistics, ICMP_MIB_OUTMSGS),
snmp_fold_field((void __percpu **) net->mib.icmp_statistics, ICMP_MIB_OUTERRORS));
for (i=0; icmpmibmap[i].name != NULL; i++)
seq_printf(seq, " %lu",
- snmp_fold_field((void __percpu **) net->mib.icmpmsg_statistics,
- icmpmibmap[i].index | 0x100));
+ atomic_long_read(ptr + (icmpmibmap[i].index | 0x100)));
}
/*