Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 6 Feb 2003 10:41:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 6 Feb 2003 10:41:55 -0500 Received: from ns.suse.de ([213.95.15.193]:38669 "EHLO Cantor.suse.de") by vger.kernel.org with ESMTP id ; Thu, 6 Feb 2003 10:41:54 -0500 Date: Thu, 6 Feb 2003 16:51:14 +0100 From: Andi Kleen To: "Martin J. Bligh" Cc: linux-kernel , lse-tech Subject: Re: [Lse-tech] gcc -O2 vs gcc -Os performance Message-ID: <20030206155114.GA16390@wotan.suse.de> References: <336780000.1044313506@flay> <224770000.1044546145@[10.10.2.4]> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <224770000.1044546145@[10.10.2.4]> User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 995 Lines: 21 > All done with gcc-2.95.4 (Debian Woody). These machines (16x NUMA-Q) have > 700MHz P3 Xeons with 2Mb L2 cache ... -Os might fare better on celeron > with a puny cache if someone wants to try that out. -Os on 2.95 is not too useful. It only started becomming useful on 3.1+, even more so on the upcomming 3.3. e.g. there was one report of ACPI shrinking by >60k by recompiling it with -Os on 3.1. ACPI is only slow path code so that is completely reasonable. Best would be of course to use profile feedback to let the compiler decide where to generate small and where to generate fast&big code. But that has problems with the maintainability (it will be hard to generate the same vmlinux as users for debugging/ksymoops reading purposes) -Andi - 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/