From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753080AbYADM0s (ORCPT ); Fri, 4 Jan 2008 07:26:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751715AbYADM0k (ORCPT ); Fri, 4 Jan 2008 07:26:40 -0500 Received: from mx2.suse.de ([195.135.220.15]:34945 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751522AbYADM0j (ORCPT ); Fri, 4 Jan 2008 07:26:39 -0500 From: Andi Kleen Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg) To: Thomas Gleixner Subject: Re: [PATCH x86] [12/16] Optimize lock prefix switching to run less frequently Date: Fri, 4 Jan 2008 13:17:30 +0100 User-Agent: KMail/1.9.6 Cc: linux-kernel@vger.kernel.org References: <20080103442.621670000@suse.de> <20080103154226.67D6414DDB@wotan.suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200801041317.30404.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 04 January 2008 10:42:17 Thomas Gleixner wrote: > On Thu, 3 Jan 2008, Andi Kleen wrote: > > This makes a significant difference in boot up performance on AMD SimNow! > > Also I expect it to be a little faster on native systems too because a smp > > switch does a lot of text_poke()s which each synchronize the pipeline. > > Please run your patches through checkpatch.pl. > > ERROR: use tabs not spaces > #48: FILE: arch/x86/kernel/alternative.c:360: I saw a lot of these warnings, but disregarded them as obviously silly. I don't have plans to redo all the patches for that. > > + > > + /* Only switch to UP mode if we don't immediately boot others */ > > + if (num_possible_cpus() == 1 || max_cpus == 0) > > Shouldn't this be max_cpus <= 1 ? Don't think so, smp_init() seems to use it one off. > > +extern unsigned int max_cpus; > > I'm a bit wary about making max_cpus global. max_cpus is used all over > the place as a local variable name. Can we please rename it to > setup_max_cpus or something like that? Hmm, I didn't see any warnings from this so surely it's not a big issue? -Andi