From: Andi Kleen <andi@firstfloor.org>
To: Timothy Shimmin <tes@sgi.com>
Cc: David Chinner <dgc@sgi.com>, Niv Sardi <xaiki@cxhome.ath.cx>,
Christoph Hellwig <hch@lst.de>,
xfs@oss.sgi.com
Subject: Re: likely and unlikely was: Re: [PATCH] split xfs_ioc_xattr
Date: Fri, 18 Apr 2008 15:34:59 +0200 [thread overview]
Message-ID: <4808A383.5050907@firstfloor.org> (raw)
In-Reply-To: <4808488A.7010204@sgi.com>
Timothy Shimmin wrote:
> Hi,
>
> Thanks for the explanation, Andi.
> So I guess the upshot is, that it can make a difference but
> in many cases (where the perf difference isn't an issue)
> it is probably not worth the ugliness.
> And in performance cases, it would be best to test the hypothesis
> with the unlikely profiler patch
> => it will be _unlikely_ we will bother ;-)
> So I don't think I'll be bothering with them then unless
> an issue comes up :)
Ideal would be to not bother by default, but occasionally
run oprofile with icache and branch misprediction profiling for macro
benchmarks (significant user space code running) and if you see
any icache miss/mispredict hot spots in your code add the annotations
there and then double check with the unlikely profiler.
-Andi
next prev parent reply other threads:[~2008-04-18 13:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-19 20:40 [PATCH] split xfs_ioc_xattr Christoph Hellwig
2008-04-14 3:14 ` Niv Sardi
2008-04-14 3:29 ` Christoph Hellwig
2008-04-16 3:47 ` Niv Sardi
2008-04-16 6:37 ` David Chinner
2008-04-16 7:06 ` Timothy Shimmin
2008-04-16 7:29 ` Andi Kleen
2008-04-18 7:06 ` likely and unlikely was: " Timothy Shimmin
2008-04-18 13:34 ` Andi Kleen [this message]
2008-04-18 14:05 ` Eric Sandeen
2008-04-21 0:33 ` David Chinner
2008-04-21 7:55 ` Andi Kleen
2008-04-21 21:41 ` David Chinner
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