Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752579AbXA2UaH (ORCPT ); Mon, 29 Jan 2007 15:30:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752588AbXA2UaH (ORCPT ); Mon, 29 Jan 2007 15:30:07 -0500 Received: from omx2-ext.sgi.com ([192.48.171.19]:43775 "EHLO omx2.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752579AbXA2UaF (ORCPT ); Mon, 29 Jan 2007 15:30:05 -0500 Date: Mon, 29 Jan 2007 12:29:15 -0800 (PST) From: Christoph Lameter To: Oleg Nesterov cc: 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 In-Reply-To: <20070129194938.GB233@tv-sign.ru> Message-ID: References: <20070129011301.GA844@tv-sign.ru> <20070129171923.GA138@tv-sign.ru> <20070129182742.GA158@tv-sign.ru> <20070129194938.GB233@tv-sign.ru> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1852 Lines: 57 On Mon, 29 Jan 2007, Oleg Nesterov wrote: > > But we could delay CPU_DOWN in the handler for the slab until we know that > > the cache_reaper is no longer running? > > Hmm... I don't undestand this. We can delay CPU_DOWN if we cancel cache_reaper > like you did in the previous patch. Did you mean this? If yes - then yes :) Yes sure. > Worse, we can have 2 handlers running in parallel on the same CPU. But this > is fixed by your previous patch, I believe. Good. Here is the patch against 2.6.20-rc6-mm2. CPU_DOWN_PREPARE and CPU_DOWN_FAILED somehow vanished in mm? Shutdown cache_reaper when cpu goes down Shutdown the cache_reaper in slab.c if the cpu is brought down and set the cache_reap.func to NULL. Otherwise hotplug shuts down the reaper for good. Signed-off-by: Christoph Lameter Index: linux-2.6.20-rc6-mm1/mm/slab.c =================================================================== --- linux-2.6.20-rc6-mm1.orig/mm/slab.c 2007-01-29 14:18:37.000000000 -0600 +++ linux-2.6.20-rc6-mm1/mm/slab.c 2007-01-29 14:21:18.119155877 -0600 @@ -1271,6 +1271,17 @@ static int __cpuinit cpuup_callback(stru start_cpu_timer(cpu); break; #ifdef CONFIG_HOTPLUG_CPU + case CPU_DOWN_PREPARE: + /* Shutdown cache reaper */ + cancel_rearming_delayed_work(&per_cpu(reap_work, cpu)); + per_cpu(reap_work, cpu).work.func = NULL; + + mutex_lock(&cache_chain_mutex); + break; + case CPU_DOWN_FAILED: + mutex_unlock(&cache_chain_mutex); + start_cpu_timer(cpu); + break; case CPU_DEAD: /* * Even if all the cpus of a node are down, we don't free the - 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/