Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932368AbWCMThR (ORCPT ); Mon, 13 Mar 2006 14:37:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932389AbWCMThQ (ORCPT ); Mon, 13 Mar 2006 14:37:16 -0500 Received: from pasmtp.tele.dk ([193.162.159.95]:21266 "EHLO pasmtp.tele.dk") by vger.kernel.org with ESMTP id S932368AbWCMThP (ORCPT ); Mon, 13 Mar 2006 14:37:15 -0500 Date: Mon, 13 Mar 2006 20:36:43 +0100 From: Sam Ravnborg To: "Bryan O'Sullivan" Cc: Adrian Bunk , rjwalsh@pathscale.com, rolandd@cisco.com, gregkh@suse.de, akpm@osdl.org, davem@davemloft.net, linux-kernel@vger.kernel.org, openib-general@openib.org Subject: Re: [PATCH 18 of 20] ipath - kbuild infrastructure Message-ID: <20060313193643.GB32349@mars.ravnborg.org> References: <867a396dd518ac63ab41.1141950948@eng-12.pathscale.com> <20060313181025.GA13973@stusta.de> <1142277868.9032.14.camel@serpentine.pathscale.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1142277868.9032.14.camel@serpentine.pathscale.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1210 Lines: 28 On Mon, Mar 13, 2006 at 11:24:28AM -0800, Bryan O'Sullivan wrote: > On Mon, 2006-03-13 at 19:10 +0100, Adrian Bunk wrote: > > > I'm still a bit surprised, since in the rest of the kernel we are even > > going from -O2 to -Os for getting better performance. > > > > Robert said he wanted to post some numbers showing that -O3 is > > measurably better for you [1], but I haven't seen them. > > I just ran some numbers. At large packet sizes, it doesn't matter what > options we use, because we spend all of our time in __iowrite_copy32, > which uses the string copy instructions. > > For small packets, my quick tests indicate that -Os gives about 5% > *better* performance than -O3 (using gcc 4 on FC4). This is in line > with what people have been finding in the kernel in general recently. > > So if I change that CFLAGS line from -O3 to -Os, are we in OK > shape? :-) Use the kernel settings. We cannot have this modified by each and every driver. Sam - 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/