linux-kernel - Re: [PATCH 0/5] [GIT PULL] ring-buffer: optimize to 17% performance increase

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Date:	Wed, 13 May 2009 09:44:56 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Ingo Molnar <mingo@...e.hu>
cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 0/5] [GIT PULL] ring-buffer: optimize to 17% performance
 increase


On Tue, 12 May 2009, Steven Rostedt wrote:

> 
> On Tue, 12 May 2009, Steven Rostedt wrote:
> > > 
> > > It's also interesting to see that text size went down when speed 
> > > went up. I'm wondering how these compiler options:
> > 
> > But that was not always the case. The biggest boost in performance of the 
> > series (the last patch) also increased the size.
> > 
> > > 
> > >   CONFIG_CC_OPTIMIZE_FOR_SIZE=y
> > >   CONFIG_OPTIMIZE_INLINING=y
> > 
> > Note, my test runs had both the above configure options disabled.
> > I'll run it again and see how they affect the results:
> 
> Here's the results:
> 
> size=n inline=n  270 
> size=n inline=y  290
> size=y inline=n  315
> size=y inline=y  372 (ouch!)
> 
> Thus it seems to keep both optimizations off is best for performance.

Versions do make a difference. I just upgraded my distcc gcc on all my 
distcc boxes from gcc 4.2.2 to 4.4.0 and here's the new results:

size=n inline=n  257
size=n inline=y  259
size=y inline=n  295
size=y inline=y  315

The gcc inlining got a little better, but adding size seems to hurt.

-- Steve

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