Date: Mon, 2 Nov 2009 11:41:24 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>,
       Rusty Russell <rusty@rustcorp.com.au>
Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
       Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH][RFC] Adding hackbench.c to tools/
Message-ID: <20091102104124.GA5193@elte.hu>
References: <20091101.131027.680961629714047921.mitake@dcl.info.waseda.ac.jp>
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* Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp> wrote:

> Hi Ingo,
> 
> It seems that hackbench is the de-fact standard benchmarking program 
> for scheduler of Linux. But when I ask google where hackbench.c is, 
> some answers are replied. Like these, (in order of google result)
> 
> http://devresources.linux-foundation.org/craiger/hackbench/ (this page 
> containts link to hackbench.c) 
> http://people.redhat.com/mingo/cfs-scheduler/tools/hackbench.c
> 
> And it seems that second one is newer.
> 
> I think this situation is very confusable. So I wrote this patch to 
> add hackbench to tools/ of kernel tree. This may help hackbench users 
> like me.

I think we can do something nicer: would you be interested in adding it 
as a 'perf bench hackbench' sub-command of tools/perf/?

We already have the tools to measure scheduling behavior under 'perf 
sched', so having a 'perf bench' array of common tests would be nice to 
have.

( I've Cc:-ed Rusty, the original author of hackbench.c. Rusty, the file 
  has no explicit GPLv2 compatible license - is it fine to be put
  into GPLv2 code? )

Adding a new perf sub-command is easy:

create a new tools/perf/builtin-bench.c file and copy hackbench.c to it, 
add it to command-list.txt and to the Makefile - add it to perf.c's 
array of built-in commands and [optional] add a 
Documentation/perf-bench.txt file to generate manpages and usage strings 
for it.

Change the 'main' function to cmd_bench() and add option parsing like 
you can see in the other builtin-*.c files. This should get you going.

Eventually we'd add more scheduler (and other) benchmarks too, not just 
hackbench. I'd also suggest to name it not 'hackbench' but something 
more generic, like:

  perf bench sched messaging

So that we can have subsystem identifier first, then the type of 
benchmark.

	Ingo
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