linux-kernel - Re: [patch 10/10] Scheduler profiling

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Message-ID: <20070706232843.GT3492@stusta.de>
Date:	Sat, 7 Jul 2007 01:28:43 +0200
From:	Adrian Bunk <bunk@...sta.de>
To:	Chuck Ebbert <cebbert@...hat.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Alexey Dobriyan <adobriyan@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 10/10] Scheduler profiling - Use immediate values

On Fri, Jul 06, 2007 at 06:14:10PM -0400, Chuck Ebbert wrote:
> On 07/06/2007 07:44 AM, Andi Kleen wrote:
> > I think the optimization is a good idea, although i dislike it
> > that it is complicated for the dynamic markers. If it was just
> > static it would be much simpler.
> 
> Another thing to consider is that there might be hundreds of these
> probes/tracepoints active in an instrumented kernel. The overhead
> adds up fast, so the gain may be worth all the pain.

Only if you want to squeeze the last bit of performance out of
_debugging_ functionality.

You avoid all the pain if you simply don't use debugging functionality 
on production systems.

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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