From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 3533F6B0044 for ; Thu, 5 Nov 2009 18:45:19 -0500 (EST) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id nA5NjGh0013439 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Fri, 6 Nov 2009 08:45:16 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 0902845DE4E for ; Fri, 6 Nov 2009 08:45:16 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id B217045DE62 for ; Fri, 6 Nov 2009 08:45:15 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 17315E78001 for ; Fri, 6 Nov 2009 08:45:15 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 8C32B1DB8046 for ; Fri, 6 Nov 2009 08:45:14 +0900 (JST) Date: Fri, 6 Nov 2009 08:42:38 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [MM] Make mm counters per cpu instead of atomic Message-Id: <20091106084238.cbecd8ef.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: <20091105101650.45204e4e.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: "hugh.dickins@tiscali.co.uk" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Tejun Heo List-ID: On Thu, 5 Nov 2009 10:10:56 -0500 (EST) Christoph Lameter wrote: > 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. > My number is just from Kconfig. > > 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. > If swap_usage is added, 24m, 25% of vmalloc area. (But, yes, returning -ENOMEM to fork() is ok to me, 65536 proc are extreme.) Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org