Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757737AbYBRSex (ORCPT ); Mon, 18 Feb 2008 13:34:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751916AbYBRSeq (ORCPT ); Mon, 18 Feb 2008 13:34:46 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:46388 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751868AbYBRSep (ORCPT ); Mon, 18 Feb 2008 13:34:45 -0500 Date: Mon, 18 Feb 2008 10:33:20 -0800 From: Arjan van de Ven To: Valdis.Kletnieks@vt.edu Cc: David Howells , Geert Uytterhoeven , Adrian Bunk , Roel Kluin <12o3l@tiscali.nl>, lkml , cbe-oss-dev@ozlabs.org, linuxppc-dev@ozlabs.org, Willy Tarreau Subject: Re: [PATCH 1/3] Fix Unlikely(x) == y Message-ID: <20080218103320.41cf096f@laptopd505.fenrus.org> In-Reply-To: <26571.1203358266@turing-police.cc.vt.edu> References: <47B70A61.9030306@tiscali.nl> <20080216092552.325e5726@laptopd505.fenrus.org> <20080216173315.GU8953@1wt.eu> <20080216094226.1e8eede1@laptopd505.fenrus.org> <47B72BFE.9060302@am.sony.com> <20080216103927.2a02352b@laptopd505.fenrus.org> <1203249003.6718.24.camel@concordia> <20080218135609.GD21080@cs181133002.pp.htv.fi> <12131.1203344830@redhat.com> <26571.1203358266@turing-police.cc.vt.edu> Organization: Intel X-Mailer: Claws Mail 3.2.0 (GTK+ 2.12.5; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 984 Lines: 27 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/