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Re: likely and unlikely was: Re: [PATCH] split xfs_ioc_xattr

To: Timothy Shimmin <tes@xxxxxxx>
Subject: Re: likely and unlikely was: Re: [PATCH] split xfs_ioc_xattr
From: Eric Sandeen <sandeen@xxxxxxxxxxx>
Date: Fri, 18 Apr 2008 09:05:25 -0500
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>, David Chinner <dgc@xxxxxxx>, Niv Sardi <xaiki@xxxxxxxxxxxxx>, Christoph Hellwig <hch@xxxxxx>, xfs@xxxxxxxxxxx
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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 :)
> 
> --Tim

ISTR that the dir2 code on Irix had tons of compiler pragmas for likely
and unlikely paths, and that it actually was well-profiled and tested.
Did that ever get translated into Linux hints?

-Eric


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