From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753067Ab3KDP42 (ORCPT ); Mon, 4 Nov 2013 10:56:28 -0500 Received: from relay1.sgi.com ([192.48.179.29]:48437 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751936Ab3KDP41 (ORCPT ); Mon, 4 Nov 2013 10:56:27 -0500 Date: Mon, 4 Nov 2013 09:56:24 -0600 From: Russ Anderson To: Josh Boyer Cc: Ingo Molnar , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , prarit@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: Allow NR_CPUS=1024 Message-ID: <20131104155624.GA31656@sgi.com> Reply-To: Russ Anderson 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131104141615.GD9944@hansolo.jdub.homelinux.org> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 04, 2013 at 09:16:16AM -0500, 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? Yes. We have a system in the lab with 254 12-core IVB sockets for a total of 3048 cores. With HT is it 6096 cpus. > If so, I can actually make a bump to the MAXSMP count a separate patch. > > josh -- Russ Anderson, OS RAS/Partitioning Project Lead SGI - Silicon Graphics Inc rja@sgi.com