From owner-cvs-src@FreeBSD.ORG Sun Oct 26 03:13:46 2003 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0EACE16A4B3; Sun, 26 Oct 2003 03:13:46 -0800 (PST) Received: from mail.broadpark.no (mail.broadpark.no [217.13.4.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id EF2C143F85; Sun, 26 Oct 2003 03:13:42 -0800 (PST) (envelope-from des@des.no) Received: from smtp.des.no (37.80-203-228.nextgentel.com [80.203.228.37]) by mail.broadpark.no (Postfix) with ESMTP id 230D979A5B; Sun, 26 Oct 2003 12:13:42 +0100 (MET) Received: by smtp.des.no (Pony Express, from userid 666) id D6E039C044; Sun, 26 Oct 2003 12:13:41 +0100 (CET) Received: from dwp.des.no (dwp.des.no [10.0.0.4]) by smtp.des.no (Pony Express) with ESMTP id 246D49BFF3; Sun, 26 Oct 2003 12:13:38 +0100 (CET) Received: by dwp.des.no (Postfix, from userid 2602) id 07946B823; Sun, 26 Oct 2003 12:13:38 +0100 (CET) To: Peter Wemm References: <20031026064145.18F0E2A8D5@canning.wemm.org> From: des@des.no (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=) Date: Sun, 26 Oct 2003 12:13:37 +0100 In-Reply-To: <20031026064145.18F0E2A8D5@canning.wemm.org> (Peter Wemm's message of "Sat, 25 Oct 2003 23:41:45 -0700") Message-ID: User-Agent: Gnus/5.090024 (Oort Gnus v0.24) Emacs/21.3 (berkeley-unix) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on dsa.des.no X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.60 cc: Jeff Roberson cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org cc: cvs-src@FreeBSD.org Subject: Re: cvs commit: src/sys/i386/i386 pmap.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 26 Oct 2003 11:13:46 -0000 Peter Wemm writes: > Massively deep pipelines help get the MHz up, and careful optimization can > stop it affecting frame rates. But it blows chunks if you mispredict a > branch in typical gcc generated code. Or take our libc syscall stubs.. > every single one will be mispredicted because the usual case (no errors) > has an opposite direction branch to what intel's static branch prediction > expects. Is there any way to teach (or trick) gcc to generate a branch which the p4 will predict correctly? DES --=20 Dag-Erling Sm=F8rgrav - des@des.no