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Groups > linux.kernel > #1477031

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

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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

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[RFC PATCH v2 0/6] Reduce cache miss for snmp_fold_field Jia He <hejianet@gmail.com> - 2016-09-06 04:40 +0200
  [RFC PATCH v2 4/6] proc: Reduce cache miss in xfrm_statistics_seq_show Jia He <hejianet@gmail.com> - 2016-09-06 04:40 +0200
  [RFC PATCH v2 6/6] net: Suppress the "Comparison to NULL could be written" warning Jia He <hejianet@gmail.com> - 2016-09-06 04:40 +0200
  [RFC PATCH v2 1/6] proc: Reduce cache miss in {snmp,netstat}_seq_show Jia He <hejianet@gmail.com> - 2016-09-06 04:40 +0200
    Re: [RFC PATCH v2 1/6] proc: Reduce cache miss in  {snmp,netstat}_seq_show David Miller <davem@davemloft.net> - 2016-09-07 01:00 +0200
      Re: [RFC PATCH v2 1/6] proc: Reduce cache miss in  {snmp,netstat}_seq_show hejianet <hejianet@gmail.com> - 2016-09-07 04:30 +0200
  [RFC PATCH v2 5/6] ipv6: Remove useless parameter in __snmp6_fill_statsdev Jia He <hejianet@gmail.com> - 2016-09-06 04:40 +0200
  [RFC PATCH v2 2/6] proc: Reduce cache miss in snmp6_seq_show Jia He <hejianet@gmail.com> - 2016-09-06 04:40 +0200
  [RFC PATCH v2 3/6] proc: Reduce cache miss in sctp_snmp_seq_show Jia He <hejianet@gmail.com> - 2016-09-06 04:40 +0200
  Re: [RFC PATCH v2 0/6] Reduce cache miss for snmp_fold_field Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> - 2016-09-06 14:50 +0200
    Re: [RFC PATCH v2 0/6] Reduce cache miss for snmp_fold_field hejianet <hejianet@gmail.com> - 2016-09-07 04:40 +0200

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