[RFC PATCH v2 3/6] proc: Reduce cache miss in sctp_snmp_seq_show

Jia He
2016-09-06T02:30:42Z

This patch exchanges the two loop for collecting the percpu
statistics data. This can reduce cache misses by going through
all the items of each cpu sequentially.

Signed-off-by: Jia He <hejianet@gmail.com>
---
net/sctp/proc.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/net/sctp/proc.c b/net/sctp/proc.c
index ef8ba77..085fb95 100644
--- a/net/sctp/proc.c
+++ b/net/sctp/proc.c
@@ -74,12 +74,19 @@ static const struct snmp_mib sctp_snmp_list[] = {
static int sctp_snmp_seq_show(struct seq_file *seq, void *v)
{
struct net *net = seq->private;
- int i;
+ int i, c;
+ unsigned long buff[SCTP_MIB_MAX];

+ memset(buff, 0, sizeof(unsigned long) * SCTP_MIB_MAX);
+
+ for_each_possible_cpu(c)
+ for (i = 0; sctp_snmp_list[i].name != NULL; i++)
+ buff[i] += snmp_get_cpu_field(
+ net->sctp.sctp_statistics,
+ c, sctp_snmp_list[i].entry);
for (i = 0; sctp_snmp_list[i].name != NULL; i++)
seq_printf(seq, "%-32s\t%ld\n", sctp_snmp_list[i].name,
- snmp_fold_field(net->sctp.sctp_statistics,
- sctp_snmp_list[i].entry));
+ buff[i]);

return 0;
}
--
1.8.3.1