Date: Fri, 18 May 2007 15:12:59 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Phillip Susi <psusi@cfl.rr.com>
Cc: Alex Volkov <avcp-lkmail@usa.net>, "'Jeff Garzik'" <jeff@garzik.org>,
       "'Linux Kernel Mailing List'" <linux-kernel@vger.kernel.org>
Subject: Re: aio is unlikely
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On Fri, 18 May 2007 17:54:32 -0400
Phillip Susi <psusi@cfl.rr.com> wrote:

> Andrew Morton wrote:
> > Yes, if you agree with Jeff's original point.
> > 
> > But I don't, actually.  Sure, on some machines+workloads, AIO is more
> > common than sync IO.  But I expect that when we sum across all the
> > machines+workloads in the world, sync IO is more common and is hence the
> > case we should optimise for.
> > 
> > That's assuming that the unlikely() actually does something.
> 
> But as Jeff said, that's not what unlikely is for.  It should only be 
> used when it is unlikely for everybody, all the time, because when it is 
> right, it helps rather little, but when it is wrong, it hurts a lot.

It does?  Tell us more.
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