From: Jeff Garzik <jgarzik@mandrakesoft.com>
To: David Schwartz <davids@webmaster.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: likely/unlikely
Date: Wed, 16 Jan 2002 00:14:50 -0500 [thread overview]
Message-ID: <3C450C4A.8A8382A6@mandrakesoft.com> (raw)
In-Reply-To: <20020116032300.AAA27749@shell.webmaster.com@whenever>
David Schwartz wrote:
>
> By the way, has anybody actually benchmarked these macros to see if they
> make any difference. I did a few quick inexact benchmarks on test code and
> found that in most cases there was no difference and in some cases code was
> made worse.
likely/unlikely set the branch prediction values to 99% or 1%
respectively. If this causes the code generated to perform less
optimally than without, I'm sure the gcc guys would be -very- interested
to hear that...
--
Jeff Garzik | Alternate titles for LOTR:
Building 1024 | Fast Times at Uruk-Hai
MandrakeSoft | The Took, the Elf, His Daughter and Her Lover
| Samwise Gamgee: International Hobbit of Mystery
next prev parent reply other threads:[~2002-01-16 5:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-16 3:22 likely/unlikely David Schwartz
2002-01-16 5:14 ` Jeff Garzik [this message]
2002-01-16 6:00 ` likely/unlikely Anton Blanchard
2002-01-16 9:12 ` likely/unlikely Jeff Garzik
2002-01-16 6:32 ` likely/unlikely Craig Christophel
2002-01-16 7:38 ` likely/unlikely Adrian Bunk
2002-01-16 9:14 ` likely/unlikely Jeff Garzik
2002-01-16 9:29 ` likely/unlikely Jens Axboe
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