From: Andrew Morton <akpm@linux-foundation.org>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Glauber Costa <glommer@parallels.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Paul Tuner <pjt@google.com>
Subject: Re: [PATCH v2] proc: speedup /proc/stat handling
Date: Tue, 24 Jan 2012 17:27:32 -0800 [thread overview]
Message-ID: <20120124172732.19b3d9f4.akpm@linux-foundation.org> (raw)
In-Reply-To: <1327450945.14373.24.camel@edumazet-laptop>
On Wed, 25 Jan 2012 01:22:25 +0100
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> Le mardi 24 janvier 2012 __ 16:12 -0800, Andrew Morton a __crit :
>
> > Did you measure the improvement from this patch?
>
> Unfortunately I can not reboot the server where I noticed this
> performance problem.
>
> On the smaller one, performance improvement is about 20%, because the
> second run of show_stat() can use data present in cpu cache.
>
> On big machines, I guess the 128 bytes per possible cpu reservation can
> avoid the second run. (since a typical cpuXXX line is smaller than 128
> bytes)
I had a fiddle on an 8-way x86_64 machine. I'm unable to demonstrate
any improvement for either of
time (for i in $(seq 1000); do; cat /proc/self/stat > /dev/null; done)
time (for i in $(seq 1000); do; cat /proc/1/stat > /dev/null; done)
oh well.
next prev parent reply other threads:[~2012-01-25 1:27 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-20 15:59 [PATCH] proc: speedup /proc/stat handling Eric Dumazet
2012-01-20 22:55 ` Andrew Morton
2012-01-23 10:16 ` KAMEZAWA Hiroyuki
2012-01-23 10:33 ` Glauber Costa
2012-01-24 1:25 ` KAMEZAWA Hiroyuki
2012-01-25 0:01 ` [PATCH v2] " Eric Dumazet
2012-01-25 0:12 ` Andrew Morton
2012-01-25 0:22 ` Eric Dumazet
2012-01-25 1:27 ` Andrew Morton [this message]
2012-01-25 5:29 ` Eric Dumazet
2012-01-26 1:04 ` Andrew Morton
2012-01-26 9:55 ` KAMEZAWA Hiroyuki
2012-01-27 0:43 ` Andrew Morton
2012-01-27 1:09 ` KAMEZAWA Hiroyuki
2012-01-27 1:18 ` Andrew Morton
2012-01-30 5:16 ` [PATCH] Add num_to_str() for speedup /proc/stat KAMEZAWA Hiroyuki
2012-01-30 23:20 ` Andrew Morton
2012-01-30 23:58 ` KAMEZAWA Hiroyuki
2012-02-01 14:43 ` Andrea Righi
2012-02-01 23:46 ` KAMEZAWA Hiroyuki
2012-01-27 7:09 ` [PATCH v2] proc: speedup /proc/stat handling Eric Dumazet
2012-01-25 0:18 ` KAMEZAWA Hiroyuki
2012-01-25 0:26 ` Eric Dumazet
2012-01-30 8:06 ` Jörg-Volker Peetz
2012-01-30 9:25 ` Eric Dumazet
2012-01-30 10:00 ` Jörg-Volker Peetz
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120124172732.19b3d9f4.akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=a.p.zijlstra@chello.nl \
--cc=eric.dumazet@gmail.com \
--cc=glommer@parallels.com \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@arm.linux.org.uk \
--cc=mingo@elte.hu \
--cc=pjt@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).