From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751469AbaLPHdf (ORCPT ); Tue, 16 Dec 2014 02:33:35 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:54036 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751035AbaLPHde (ORCPT ); Tue, 16 Dec 2014 02:33:34 -0500 X-SecurityPolicyCheck: OK by SHieldMailChecker v2.2.3 X-SHieldMailCheckerPolicyVersion: FJ-ISEC-20140219-2 Message-ID: <548FDFF3.8090705@jp.fujitsu.com> Date: Tue, 16 Dec 2014 16:32:03 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Lai Jiangshan CC: , Tejun Heo , Yasuaki Ishimatsu , "Gu, Zheng" , tangchen Subject: Re: [PATCH 1/4] workqueue:Fix unbound workqueue's node affinity detection References: <1418379595-6281-1-git-send-email-laijs@cn.fujitsu.com> <548C68DA.20507@jp.fujitsu.com> <548EC1E2.1010101@jp.fujitsu.com> <548EC29A.5080008@jp.fujitsu.com> <548FC378.6060809@cn.fujitsu.com> In-Reply-To: <548FC378.6060809@cn.fujitsu.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-SecurityPolicyCheck-GC: OK by FENCE-Mail Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/12/16 14:30), Lai Jiangshan wrote: > On 12/15/2014 07:14 PM, Kamezawa Hiroyuki wrote: >> Unbound wq pool's node attribute is calculated at its allocation. >> But it's now calculated based on possible cpu<->node information >> which can be wrong after cpu hotplug/unplug. >> >> If wrong pool->node is set, following allocation error will happen. >> == >> SLUB: Unable to allocate memory on node 2 (gfp=0x80d0) >> cache: kmalloc-192, object size: 192, buffer size: 192, default order: >> 1, min order: 0 >> node 0: slabs: 6172, objs: 259224, free: 245741 >> node 1: slabs: 3261, objs: 136962, free: 127656 >> == >> >> This patch fixes the node detection by making use of online cpu info. >> Unlike cpumask, the best node can be calculated by degree of overlap >> between attr->cpumask and numanode->online_cpumask. >> This change doesn't corrupt original purpose of the old calculation. >> >> Note: it's expected that this function is called as >> pool_detect_best_node >> get_unbound_pool >> alloc_unbound_pwq >> wq_update_unbound_numa >> called at CPU_ONLINE/CPU_DOWN_PREPARE >> and the latest online cpu info can be applied to a new wq pool, >> which replaces old one. >> >> Signed-off-by: KAMEZAWA Hiroyuki >> --- >> kernel/workqueue.c | 38 ++++++++++++++++++++++++++------------ >> 1 file changed, 26 insertions(+), 12 deletions(-) >> >> diff --git a/kernel/workqueue.c b/kernel/workqueue.c >> index 09b685d..7809154 100644 >> --- a/kernel/workqueue.c >> +++ b/kernel/workqueue.c >> @@ -3440,6 +3440,31 @@ static void put_unbound_pool(struct worker_pool *pool) >> } >> >> /** >> + * pool_detect_best_node - detect a node which contains specified cpumask. >> + * Should be called with wq_pool_mutex held. >> + * Returns a online node where the most of given cpus are tied to. >> + */ >> +static int pool_detect_best_node(const struct cpumask *cpumask) >> +{ >> + int node, best, match, selected = NUMA_NO_NODE; >> + static struct cpumask andmask; /* under wq_pool_mutex */ >> + >> + if (!wq_numa_enabled || >> + cpumask_subset(cpu_online_mask, cpumask)) >> + goto out; >> + best = 0; >> + /* select a node which contains the most number of cpu */ >> + for_each_node_state(node, N_ONLINE) { >> + cpumask_and(&andmask, cpumask, cpumask_of_node(node)); >> + match = cpumask_weight(&andmask); >> + if (match > best) >> + selected = best; >> + } >> +out: >> + return selected; >> +} > > > This is a mixture of fix and development. Why not just keep the original calculation? > Just because wq_numa_possible_mask is broken, it shouldn't be used if possible. In this patch series, the mask is updated only when a node is coming up. Is it better to clear it at node offline ? > if the mask cover multiple nodes, NUMA_NO_NODE is the best for pool->node > after the pool was created. The memory allocation will select the best node > for manage_workers(), from which CPU that the worker actually is running on. > I'll drop this and try to keep original code as much as possible. Thanks, -Kame