Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030480AbXBTWCZ (ORCPT ); Tue, 20 Feb 2007 17:02:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030479AbXBTWCZ (ORCPT ); Tue, 20 Feb 2007 17:02:25 -0500 Received: from ithilien.qualcomm.com ([129.46.51.59]:41348 "EHLO ithilien.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030480AbXBTWCY (ORCPT ); Tue, 20 Feb 2007 17:02:24 -0500 Message-ID: <45DB6FC7.60502@qualcomm.com> Date: Tue, 20 Feb 2007 14:01:43 -0800 From: Max Krasnyansky User-Agent: Thunderbird 2.0b2 (X11/20070116) MIME-Version: 1.0 To: Christoph Lameter CC: Oleg Nesterov , Ingo Molnar , Srivatsa Vaddagiri , "Pallipadi, Venkatesh" , Gautham shenoy , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: slab: start_cpu_timer/cache_reap CONFIG_HOTPLUG_CPU problems References: <20070129011301.GA844@tv-sign.ru> <20070129171923.GA138@tv-sign.ru> <20070129182742.GA158@tv-sign.ru> <45DB404C.4070305@qualcomm.com> <20070220200550.GA85@tv-sign.ru> <45DB669B.2010307@qualcomm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1219 Lines: 28 Christoph Lameter wrote: > On Tue, 20 Feb 2007, Max Krasnyansky wrote: > >> I guess I kind of hijacked the thread. The second part of my first email was >> dropped. Basically I was saying that I'm working on CPU isolation extensions. >> Where an isolated CPU is not supposed to do much kernel work. In which case >> you'd want to run slab cache reaper on some other CPU on behalf of the >> isolated >> one. Hence the proposal to explicitly pass cpu_id to the reaper. I guess now >> that you guys fixed the hotplug case it does not help in that scenario. > > A cpu must have a per cpu cache in order to do slab allocations. The > locking in the slab allocator depends on it. > > If the isolated cpus have no need for slab allocations then you will also > not need to run the slab_reaper(). Ok. Sounds like disabling cache_reaper is a better option for now. Like you said it's unlikely that slabs will grow much if that cpu is not heavily used by the kernel. Thanks Max - 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/