From owner-cvs-src@FreeBSD.ORG Tue Jul 22 16:07:55 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 17FCE37B401 for ; Tue, 22 Jul 2003 16:07:55 -0700 (PDT) Received: from ns1.xcllnt.net (209-128-86-226.bayarea.net [209.128.86.226]) by mx1.FreeBSD.org (Postfix) with ESMTP id 452A943FB1 for ; Tue, 22 Jul 2003 16:07:54 -0700 (PDT) (envelope-from marcel@xcllnt.net) Received: from athlon.pn.xcllnt.net (athlon.pn.xcllnt.net [192.168.4.3]) by ns1.xcllnt.net (8.12.9/8.12.9) with ESMTP id h6MN7VwO015996; Tue, 22 Jul 2003 16:07:31 -0700 (PDT) (envelope-from marcel@piii.pn.xcllnt.net) Received: from athlon.pn.xcllnt.net (localhost [127.0.0.1]) by athlon.pn.xcllnt.net (8.12.9/8.12.9) with ESMTP id h6MN7Vw9061606; Tue, 22 Jul 2003 16:07:31 -0700 (PDT) (envelope-from marcel@athlon.pn.xcllnt.net) Received: (from marcel@localhost) by athlon.pn.xcllnt.net (8.12.9/8.12.9/Submit) id h6MN7VO4061605; Tue, 22 Jul 2003 16:07:31 -0700 (PDT) (envelope-from marcel) Date: Tue, 22 Jul 2003 16:07:31 -0700 From: Marcel Moolenaar To: Poul-Henning Kamp Message-ID: <20030722230731.GB61493@athlon.pn.xcllnt.net> References: <3F1DBD05.A4886D5E@imimic.com> <16119.1058914594@critter.freebsd.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16119.1058914594@critter.freebsd.dk> User-Agent: Mutt/1.5.4i cc: "Alan L. Cox" cc: src-committers@FreeBSD.org cc: Bosko Milekic cc: Bruce Evans cc: cvs-src@FreeBSD.org cc: Steve Kargl cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern init_main.c kern_malloc.c md5c.c subr_autoconf.c subr_mbuf.c subr_prf.c tty_subr.c vfs_cluster.c vfs_subr.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: Tue, 22 Jul 2003 23:07:55 -0000 On Wed, Jul 23, 2003 at 12:56:34AM +0200, Poul-Henning Kamp wrote: > > And the only two criteria I think are trivial to use for proving an > actual benefit is: > 1. less code is generated. > 2. it runs faster in tests. criterium 1 is the worst possible. Only criterium 2 makes sense. ia64 specifically moves all the hard work to the compiler. It's not unsurprising that a normal -O yields marginal performance. Only when one takes advantage of speculation, prefetching and optimization techniques that increase ILP (which most of the time imply code expansion -- loop unrolling, inlining, code duplication) will you see a performance increase. The old gcc metric of less code is better has been demonstrated to not work in general nowadays. -- Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net