From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753614Ab3KDOzF (ORCPT ); Mon, 4 Nov 2013 09:55:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:8460 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752554Ab3KDOzD (ORCPT ); Mon, 4 Nov 2013 09:55:03 -0500 Message-ID: <5277B53D.7030100@redhat.com> Date: Mon, 04 Nov 2013 09:54:53 -0500 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110419 Red Hat/3.1.10-1.el6_0 Thunderbird/3.1.10 MIME-Version: 1.0 To: Josh Boyer CC: Ingo Molnar , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, Russ Anderson Subject: Re: [PATCH] x86: Allow NR_CPUS=1024 References: <20131101141148.GH8652@hansolo.jdub.homelinux.org> <20131103101825.GA6605@gmail.com> <20131103102132.GA6807@gmail.com> <20131103155729.GB9944@hansolo.jdub.homelinux.org> <20131104065343.GC13030@gmail.com> <20131104140141.GC9944@hansolo.jdub.homelinux.org> <20131104141051.GA19355@gmail.com> <20131104141615.GD9944@hansolo.jdub.homelinux.org> In-Reply-To: <20131104141615.GD9944@hansolo.jdub.homelinux.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/04/2013 09:16 AM, Josh Boyer wrote: > On Mon, Nov 04, 2013 at 03:10:51PM +0100, Ingo Molnar wrote: >> >> * Josh Boyer wrote: >> >>>> Why touch MAXSMP at all? It's really just a shortcut for 'configure >>>> the kernel silly large', via a single option, nothing else. You are >>>> not forced to use it and it should not affect configurability of >>>> NR_CPUS. >>>> >>>> What we _really_ want here is to fix NR_CPUS setting: to extend its >>>> range and to enforce that NR_CPUS cannot be set larger than 512 >>>> without setting CONFIG_CPUMASK_OFFSTACK. >>> >>> OK. I was just thinking that if we've come to the conclusion that 4096 >>> CPUs isn't silly large anymore, we should make MAXSMP be something we >>> consider silly large. [...] >> >> MAXSMP is also supposed to track the real hardware max as well on x86 - >> i.e. we should only increase it to 8192 etc. if such hardware exists. > > Russ, does SGI (or anyone else that you know of) have x86 hardware with > more than 4096 CPUs? I can answer this for Russ. Yes, SGI has boxes that hit 5120. P. > > If so, I can actually make a bump to the MAXSMP count a separate patch. > > josh