linux-kernel - Re: [PATCH v5 0/7] Reduce cache miss for snmp_fold

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Message-Id: <20160928.050817.110671274247345232.davem@davemloft.net>
Date:   Wed, 28 Sep 2016 05:08:17 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     hejianet@...il.com
Cc:     netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
        linux-kernel@...r.kernel.org, kuznet@....inr.ac.ru,
        jmorris@...ei.org, yoshfuji@...ux-ipv6.org, kaber@...sh.net,
        vyasevich@...il.com, nhorman@...driver.com,
        steffen.klassert@...unet.com, herbert@...dor.apana.org.au,
        marcelo.leitner@...il.com
Subject: Re: [PATCH v5 0/7] Reduce cache miss for snmp_fold_field

From: Jia He <hejianet@...il.com>
Date: Wed, 28 Sep 2016 14:22:21 +0800

> v5:
> - order local variables from longest to shortest line

I still see many cases where this problem still exists.  Please
do not resubmit this patch series until you fix all of them.

Patch #2:

-static int snmp_seq_show(struct seq_file *seq, void *v)
+static int snmp_seq_show_ipstats(struct seq_file *seq, void *v)
 {
 	int i;
+	u64 buff64[IPSTATS_MIB_MAX];
 	struct net *net = seq->private;

The order should be "net" then "buff64" then "i".

+static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v)
+{
+	int i;
+	struct net *net = seq->private;
+	unsigned long buff[TCPUDP_MIB_MAX];

The order should be "buff", "net", then "i".

Patch #3:

@@ -192,13 +197,19 @@ static void snmp6_seq_show_item(struct seq_file *seq, void __percpu *pcpumib,
 				const struct snmp_mib *itemlist)
 {
 	int i;
-	unsigned long val;
-
 ...
+	unsigned long buff[SNMP_MIB_MAX];

The order should be "buff" then "i".

@@ -206,10 +217,13 @@ static void snmp6_seq_show_item64(struct seq_file *seq, void __percpu *mib,
 				  const struct snmp_mib *itemlist, size_t syncpoff)
 {
 	int i;
+	u64 buff64[SNMP_MIB_MAX];

Likewise.

I cannot be any more explicit in my request than this.