From owner-freebsd-hackers@FreeBSD.ORG Mon Feb 16 13:12:18 2004 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7FB7116A4CE for ; Mon, 16 Feb 2004 13:12:18 -0800 (PST) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 59C4943D2D for ; Mon, 16 Feb 2004 13:12:18 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (localhost [127.0.0.1]) i1GLCF82087317; Mon, 16 Feb 2004 13:12:15 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.12.9p2/8.12.9/Submit) id i1GLCFMV087316; Mon, 16 Feb 2004 13:12:15 -0800 (PST) (envelope-from dillon) Date: Mon, 16 Feb 2004 13:12:15 -0800 (PST) From: Matthew Dillon Message-Id: <200402162112.i1GLCFMV087316@apollo.backplane.com> To: "Juan Tumani" References: cc: des@des.no cc: freebsd-hackers@freebsd.org Subject: Re: FreeBSD 5.2 v/s FreeBSD 4.9 MFLOPS performance (gcc3.3.3 v/sgcc2.9.5) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Feb 2004 21:12:18 -0000 I'm surprised Bruce hasn't chimed in here yet. I guess he's tired of repeating himself. In 4.9, libcsu, which generates crt1.o (which is the start code for C programs which the linker links in automatically) has this line in it: andl $~0xf, %%esp # align stack to 16-byte boundary So anything linked with 4.9 is going to align the stack on a 16 byte boundary no matter WHAT the kernel does. FreeBSD-5 does not have this alignment in its crt1.o because GCC3 automatically aligns the stack on a per-procedure basis. Or at least it is supposed to. Maybe it's broke? :-) -Matt