From owner-cvs-src@FreeBSD.ORG Mon Nov 10 20:31:56 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 1E55016A4CF for ; Mon, 10 Nov 2003 20:31:56 -0800 (PST) Received: from vette.gigo.com (vette.gigo.com [216.218.228.114]) by mx1.FreeBSD.org (Postfix) with ESMTP id 97E1F43FA3 for ; Mon, 10 Nov 2003 20:31:51 -0800 (PST) (envelope-from lioux@brturbo.com) Received: from 200.101.111.208 (200-101-111-208.bsace705.dsl.brasiltelecom.net.br [200.101.111.208]) by vette.gigo.com (Postfix) with ESMTP id DF68D54C9 for ; Mon, 10 Nov 2003 20:30:33 -0800 (PST) Received: (qmail 31932 invoked by uid 1001); 11 Nov 2003 04:14:42 -0000 Message-ID: <20031111041442.31931.qmail@exxodus.fedaykin.here> Received: (qmail 74326 invoked from network); 26 Oct 2003 11:47:31 -0000 Received: from unknown (HELO localhost) (unknown) by unknown with SMTP; 26 Oct 2003 11:47:31 -0000 Received: from pop3.uol.com.br by localhost with POP3 (fetchmail-6.2.5) for lioux-freebsd@localhost (single-drop); Sun, 26 Oct 2003 09:47:09 -0200 (BRST) Received: from peart.uol.com.br (172.26.5.121) by mtauol7.mail.sys.intranet (5.1.071) id 3EDB5C0C01D6FA77 for lioux-freebsd@uol.com.br; Sun, 26 Oct 2003 08:18:42 -0300 Received: from mx2.freebsd.org (mx2.freebsd.org [216.136.204.119]) by storm12.uol.com.br (Postfix) with ESMTP id 7B9A7D83A for ; Sun, 26 Oct 2003 09:18:42 -0200 (BRST) Received: from hub.freebsd.org (hub.freebsd.org [216.136.204.18]) by mx2.freebsd.org (Postfix) with ESMTP id B835556547 for ; Sun, 26 Oct 2003 03:18:41 -0800 (PST) (envelope-from owner-src-committers@FreeBSD.org) Received: by hub.freebsd.org (Postfix) id E43CD16A523; Sun, 26 Oct 2003 03:18:38 -0800 (PST) Delivered-To: lioux@freebsd.org Received: by hub.freebsd.org (Postfix, from userid 538) id 275FE16A4C0; Sun, 26 Oct 2003 03:18:38 -0800 (PST) Delivered-To: src-committers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9D53816A4B3; Sun, 26 Oct 2003 03:18:06 -0800 (PST) Received: from mail.chesapeake.net (chesapeake.net [208.142.252.6]) by mx1.FreeBSD.org (Postfix) with ESMTP id CDDC543FA3; Sun, 26 Oct 2003 03:18:04 -0800 (PST) (envelope-from jroberson@chesapeake.net) Received: from localhost (jroberson@localhost) by mail.chesapeake.net (8.11.6/8.11.6) with ESMTP id h9QBI1q01829; Sun, 26 Oct 2003 06:18:01 -0500 (EST) (envelope-from jroberson@chesapeake.net) From: Jeff Roberson To: Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?= In-Reply-To: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=X-UNKNOWN Content-Transfer-Encoding: QUOTED-PRINTABLE Sender: owner-src-committers@FreeBSD.org Precedence: bulk X-Loop: FreeBSD.ORG cc: cvs-src@FreeBSD.org cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org cc: Peter Wemm Subject: Re: cvs commit: src/sys/i386/i386 pmap.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Date: Tue, 11 Nov 2003 04:31:56 -0000 X-Original-Date: Sun, 26 Oct 2003 06:18:01 -0500 (EST) X-List-Received-Date: Tue, 11 Nov 2003 04:31:56 -0000 On Sun, 26 Oct 2003, Dag-Erling [iso-8859-1] Sm=F8rgrav wrote: > 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 predicti= on > > expects. > > Is there any way to teach (or trick) gcc to generate a branch which > the p4 will predict correctly? I doubt the effect would be measurable. We could simply rearrange the code. I do not know why it is arranged the way it is now but you would expect that there is some good reason. > > DES > -- > Dag-Erling Sm=F8rgrav - des@des.no >