From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030262AbVLMWYG (ORCPT ); Tue, 13 Dec 2005 17:24:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030261AbVLMWYG (ORCPT ); Tue, 13 Dec 2005 17:24:06 -0500 Received: from omx2-ext.sgi.com ([192.48.171.19]:489 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S1030262AbVLMWYE (ORCPT ); Tue, 13 Dec 2005 17:24:04 -0500 Date: Tue, 13 Dec 2005 14:23:46 -0800 From: Paul Jackson To: Eric Dumazet Cc: clameter@engr.sgi.com, akpm@osdl.org, linux-kernel@vger.kernel.org, nickpiggin@yahoo.com.au, Simon.Derr@bull.net, ak@suse.de Subject: Re: [PATCH] Cpuset: rcu optimization of page alloc hook Message-Id: <20051213142346.ccd3081a.pj@sgi.com> In-Reply-To: <439F3F6E.6010701@cosmosbay.com> References: <20051211233130.18000.2748.sendpatchset@jackhammer.engr.sgi.com> <439D39A8.1020806@cosmosbay.com> <20051212020211.1394bc17.pj@sgi.com> <20051212021247.388385da.akpm@osdl.org> <20051213075345.c39f335d.pj@sgi.com> <439EF75D.50206@cosmosbay.com> <439F0B43.4080500@cosmosbay.com> <20051213130350.464a3054.pj@sgi.com> <439F3F6E.6010701@cosmosbay.com> Organization: SGI X-Mailer: Sylpheed version 2.1.7 (GTK+ 2.4.9; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Eric wrote: > struct kmem_cache itself will be about 512*8 + some bytes > then for each cpu a 'struct array_cache' will be allocated (count 128 bytes Hmmm ... 'struct array_cache' looks to be about 6 integer words, so if that is the main per-CPU cost, the minimal cost of a slab cache (once created, before use) is about 24 bytes per cpu. But whether its 24 or 128 bytes per cpu, that's a heavier weight hammer than is needed here. Time for me to learn more about rcu. Thanks for raising this issue. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.925.600.0401