Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758130AbZKESC5 (ORCPT ); Thu, 5 Nov 2009 13:02:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757974AbZKESC4 (ORCPT ); Thu, 5 Nov 2009 13:02:56 -0500 Received: from smtp4.ultrahosting.com ([74.213.175.253]:44898 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757657AbZKESC4 (ORCPT ); Thu, 5 Nov 2009 13:02:56 -0500 Date: Thu, 5 Nov 2009 10:10:56 -0500 (EST) From: Christoph Lameter X-X-Sender: cl@V090114053VZO-1 To: KAMEZAWA Hiroyuki cc: "hugh.dickins@tiscali.co.uk" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Tejun Heo Subject: Re: [MM] Make mm counters per cpu instead of atomic In-Reply-To: <20091105101650.45204e4e.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20091105101650.45204e4e.kamezawa.hiroyu@jp.fujitsu.com> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 707 Lines: 20 On Thu, 5 Nov 2009, KAMEZAWA Hiroyuki wrote: > Hmm, I don't fully understand _new_ percpu but... > In logical (even if not realistic), x86-32 supports up to 512 ? cpus in Kconfig. > BIGSMP. x86-32 only supports 32 processors. Plus per cpu areas are only allocated for the possible processors. > Then, if 65536 process runs, this consumes > > 65536(nr_proc) * 8 (size) * 512(cpus) = 256MBytes. With 32 possible cpus this results in 16m of per cpu space use. -- 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/