From: Mike Galbraith <bitbucket@online.de>
To: Dave Chiluk <chiluk@canonical.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org
Subject: Re: Scheduler accounting inflated for io bound processes.
Date: Tue, 25 Jun 2013 19:48:54 +0200 [thread overview]
Message-ID: <1372182534.7497.129.camel@marge.simpson.net> (raw)
In-Reply-To: <1372176104.7497.86.camel@marge.simpson.net>
On Tue, 2013-06-25 at 18:01 +0200, Mike Galbraith wrote:
> On Thu, 2013-06-20 at 14:46 -0500, Dave Chiluk wrote:
> > Running the below testcase shows each process consuming 41-43% of it's
> > respective cpu while per core idle numbers show 63-65%, a disparity of
> > roughly 4-8%. Is this a bug, known behaviour, or consequence of the
> > process being io bound?
>
> All three I suppose.
P.S.
perf top --sort=comm -C 3 -d 5 -F 250 (my tick freq)
56.65% netserver
43.35% pert
perf top --sort=comm -C 3 -d 5
67.16% netserver
32.84% pert
If you sample a high freq signal (netperf TCP_RR) at low freq (tick),
then try to reproduce the original signal, (very familiar) distortion
results. Perf doesn't even care about softirq yada yada, so seems it's
a pure sample rate thing.
-Mike
next prev parent reply other threads:[~2013-06-25 17:49 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 19:46 Dave Chiluk
2013-06-25 16:01 ` Mike Galbraith
2013-06-25 17:48 ` Mike Galbraith [this message]
2013-06-26 9:37 ` Ingo Molnar
2013-06-26 10:42 ` Peter Zijlstra
2013-06-26 15:50 ` Ingo Molnar
2013-06-26 16:01 ` Mike Galbraith
2013-06-26 16:04 ` David Ahern
2013-06-26 16:10 ` Ingo Molnar
2013-06-26 16:13 ` David Ahern
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=1372182534.7497.129.camel@marge.simpson.net \
--to=bitbucket@online.de \
--cc=chiluk@canonical.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
/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
Powered by JetHome