Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759472Ab0FJQSo (ORCPT ); Thu, 10 Jun 2010 12:18:44 -0400 Received: from tomts13.bellnexxia.net ([209.226.175.34]:48047 "EHLO tomts13-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751907Ab0FJQSm (ORCPT ); Thu, 10 Jun 2010 12:18:42 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvsEAN+oEExGGOJc/2dsb2JhbACeXHK+b4UYBA Date: Thu, 10 Jun 2010 12:13:39 -0400 From: Mathieu Desnoyers To: Jason Baron Cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, hpa@zytor.com, tglx@linutronix.de, rostedt@goodmis.org, andi@firstfloor.org, roland@redhat.com, rth@redhat.com, mhiramat@redhat.com, fweisbec@gmail.com, avi@redhat.com, davem@davemloft.net, vgoyal@redhat.com, sam@ravnborg.org Subject: Re: [PATCH 03/13] jump label v9: x86 support Message-ID: <20100610161339.GA20448@Krystal> References: <1276171930.2077.200.camel@twins> <20100610121440.GA20130@elte.hu> <20100610150422.GA3923@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20100610150422.GA3923@redhat.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.27.31-grsec (i686) X-Uptime: 12:12:21 up 64 days, 2:05, 2 users, load average: 0.65, 0.25, 0.12 User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1255 Lines: 38 * Jason Baron (jbaron@redhat.com) wrote: > On Thu, Jun 10, 2010 at 02:14:40PM +0200, Ingo Molnar wrote: > > * Peter Zijlstra wrote: > > > > > On Wed, 2010-06-09 at 17:39 -0400, Jason Baron wrote: > > > > + select HAVE_ARCH_JUMP_LABEL if !CC_OPTIMIZE_FOR_SIZE > > > > > > That deserves a comment somewhere, it basically makes OPTIMIZE_FOR_SIZE > > > useless... > > > > Hm, we need more than a comment for that - distros enable CC_OPTIMIZE_FOR_SIZE > > all the time, for the massive kernel image (and hotpath cache footprint) > > savings. Is this fixable? > > > > Thanks, > > > > Ingo > > > > When I tested 'jump label' with CC_OPTIMIZE_FOR_SIZE, I saw a small > performance drop , b/c there is less block re-ordering happening. Is this a performance drop compared to a jump-label-less kernel or compared to -O2 kernel compiled with jump labels ? Or both ? Mathieu -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com -- 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/