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From: Arjan van de Ven <arjan@infradead.org>
To: Valdis.Kletnieks@vt.edu
Cc: David Howells <dhowells@redhat.com>,
Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>,
Adrian Bunk <bunk@kernel.org>, Roel Kluin <12o3l@tiscali.nl>,
lkml <linux-kernel@vger.kernel.org>,
cbe-oss-dev@ozlabs.org, linuxppc-dev@ozlabs.org,
Willy Tarreau <w@1wt.eu>
Subject: Re: [PATCH 1/3] Fix Unlikely(x) == y
Date: Mon, 18 Feb 2008 10:33:20 -0800 [thread overview]
Message-ID: <20080218103320.41cf096f@laptopd505.fenrus.org> (raw)
In-Reply-To: <26571.1203358266@turing-police.cc.vt.edu>
On Mon, 18 Feb 2008 13:11:06 -0500
Valdis.Kletnieks@vt.edu wrote:
> On Mon, 18 Feb 2008 14:27:10 GMT, David Howells said:
>
> > __builtin_expect() is useful on FRV where you _have_ to give each
> > branch and conditional branch instruction a measure of probability
> > whether the branch will be taken.
>
> What does gcc do the 99.998% of the time we don't have
> likely/unlikely coded?
see Andi's email.
It gets the exact same hints that 95%+ of the kernels unlikely/likely get you,
because the heuristics in it are usually the same as the kernel programmers
heuristics.
--
If you want to reach me at my work email, use arjan@linux.intel.com
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
next prev parent reply other threads:[~2008-02-18 18:34 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-16 16:08 Roel Kluin
2008-02-16 17:25 ` Arjan van de Ven
2008-02-16 17:33 ` Willy Tarreau
2008-02-16 17:42 ` Arjan van de Ven
2008-02-16 17:58 ` Willy Tarreau
2008-02-16 18:29 ` Arjan van de Ven
2008-02-17 9:45 ` [Cbe-oss-dev] " Andrew Pinski
2008-02-17 10:08 ` Willy Tarreau
2008-02-16 18:31 ` Geoff Levand
2008-02-16 18:39 ` Arjan van de Ven
2008-02-17 11:50 ` Michael Ellerman
2008-02-18 13:56 ` Adrian Bunk
2008-02-18 14:01 ` Geert Uytterhoeven
2008-02-18 14:13 ` Adrian Bunk
2008-02-18 21:46 ` Michael Ellerman
2008-02-19 7:43 ` Adrian Bunk
2008-02-18 19:22 ` [Cbe-oss-dev] " Andrew Pinski
2008-02-18 14:27 ` David Howells
2008-02-18 14:59 ` Roel Kluin
2008-02-18 18:11 ` Valdis.Kletnieks
2008-02-18 18:33 ` Arjan van de Ven [this message]
2008-02-18 14:39 ` Andi Kleen
2008-02-19 2:33 ` Nick Piggin
2008-02-19 2:40 ` Arjan van de Ven
2008-02-19 4:41 ` Nick Piggin
2008-02-19 5:58 ` Willy Tarreau
2008-02-19 6:20 ` Nick Piggin
2008-02-19 9:28 ` Andi Kleen
2008-02-20 7:32 ` Willy Tarreau
2008-02-19 9:25 ` Andi Kleen
2008-02-19 9:46 ` Nick Piggin
2008-02-19 9:57 ` Andi Kleen
2008-02-19 22:25 ` Nick Piggin
2008-02-16 18:41 ` Geoff Levand
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