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Date: Tue, 24 Nov 2009 15:39:23 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org,
       fweisbec@gmail.com, a.p.zijlstra@chello.nl, efault@gmx.de,
       tglx@linutronix.de, linux-tip-commits@vger.kernel.org
Subject: Re: [tip:tracing/core] ring-buffer benchmark: Run producer/consumer
 threads at nice +19
Message-ID: <20091124143923.GA17934@elte.hu>
References: <new-submission>
 <tip-98e4833ba3c314c99dc364012fba6ac894230ad0@git.kernel.org>
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* Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 2009-11-23 at 07:15 +0000, tip-bot for Ingo Molnar wrote:
> > Commit-ID:  98e4833ba3c314c99dc364012fba6ac894230ad0
> > Gitweb:     http://git.kernel.org/tip/98e4833ba3c314c99dc364012fba6ac894230ad0
> > Author:     Ingo Molnar <mingo@elte.hu>
> > AuthorDate: Mon, 23 Nov 2009 08:03:09 +0100
> > Committer:  Ingo Molnar <mingo@elte.hu>
> > CommitDate: Mon, 23 Nov 2009 08:03:09 +0100
> > 
> > ring-buffer benchmark: Run producer/consumer threads at nice +19
> > 
> > The ring-buffer benchmark threads run on nice 0 by default, using
> > up a lot of CPU time and slowing down the system:
> > 
> >    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> >   1024 root      20   0     0    0    0 D 95.3  0.0   4:01.67 rb_producer
> >   1023 root      20   0     0    0    0 R 93.5  0.0   2:54.33 rb_consumer
> >  21569 mingo     40   0 14852 1048  772 R  3.6  0.1   0:00.05 top
> >      1 root      40   0  4080  928  668 S  0.0  0.0   0:23.98 init
> > 
> > Renice them to +19 to make them less intrusive.
> 
> Ingo, that is the point of a benchmark!
> 
> This module is not made to be run all the time. I know you do it for 
> testing. But running it at lowest priority kills the reason this 
> module was made in the first place!

Well, it also found quite a few bugs in the ring-buffer code, beyond 
benchmarking so i'd like to use it even without looking at the numbers.

	Ingo