Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751314AbaLOC4S (ORCPT ); Sun, 14 Dec 2014 21:56:18 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:44141 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750713AbaLOC4M (ORCPT ); Sun, 14 Dec 2014 21:56:12 -0500 X-SecurityPolicyCheck: OK by SHieldMailChecker v2.2.3 X-SHieldMailCheckerPolicyVersion: FJ-ISEC-20140219-2 Message-ID: <548E4DBF.7090406@jp.fujitsu.com> Date: Mon, 15 Dec 2014 11:55:59 +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 4/4] workqueue: handle change in cpu-node relationship. References: <1418379595-6281-1-git-send-email-laijs@cn.fujitsu.com> <548C68DA.20507@jp.fujitsu.com> <548C6B72.5080302@jp.fujitsu.com> <548E4388.5090308@cn.fujitsu.com> <548E4578.3070209@jp.fujitsu.com> <548E4BF7.3000605@cn.fujitsu.com> In-Reply-To: <548E4BF7.3000605@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 (2014/12/15 11:48), Lai Jiangshan wrote: > On 12/15/2014 10:20 AM, Kamezawa Hiroyuki wrote: >> (2014/12/15 11:12), Lai Jiangshan wrote: >>> On 12/14/2014 12:38 AM, Kamezawa Hiroyuki wrote: >>>> Although workqueue detects relationship between cpu<->node at boot, >>>> it is finally determined in cpu_up(). >>>> This patch tries to update pool->node using online status of cpus. >>>> >>>> 1. When a node goes down, clear per-cpu pool's node attr. >>>> 2. When a cpu comes up, update per-cpu pool's node attr. >>>> 3. When a cpu comes up, update possinle node cpumask workqueue is using for sched. >>>> 4. Detect the best node for unbound pool's cpumask using the latest info. >>>> >>>> Signed-off-by: KAMEZAWA Hiroyuki >>>> --- >>>> kernel/workqueue.c | 67 ++++++++++++++++++++++++++++++++++++++++++------------ >>>> 1 file changed, 53 insertions(+), 14 deletions(-) >>>> >>>> diff --git a/kernel/workqueue.c b/kernel/workqueue.c >>>> index 07b4eb5..259b3ba 100644 >>>> --- a/kernel/workqueue.c >>>> +++ b/kernel/workqueue.c >>>> @@ -266,7 +266,8 @@ struct workqueue_struct { >>>> static struct kmem_cache *pwq_cache; >>>> >>>> static cpumask_var_t *wq_numa_possible_cpumask; >>>> - /* possible CPUs of each node */ >>>> + /* possible CPUs of each node initialized with possible info at boot. >>>> + but modified at cpu hotplug to be adjusted to real info. */ >>>> >>>> static bool wq_disable_numa; >>>> module_param_named(disable_numa, wq_disable_numa, bool, 0444); >>>> @@ -3449,6 +3450,31 @@ static void put_unbound_pool(struct worker_pool *pool) >>>> call_rcu_sched(&pool->rcu, rcu_free_pool); >>>> } >>>> >>>> +/* >>>> + * detect best node for given cpumask. >>>> + */ >>>> +static int pool_detect_best_node(const struct cpumask *cpumask) >>>> +{ >>>> + int node, best, match, selected; >>>> + static struct cpumask andmask; /* we're under mutex */ >>>> + >>>> + /* Is any node okay ? */ >>>> + if (!wq_numa_enabled || >>>> + cpumask_subset(cpu_online_mask, cpumask)) >>>> + return NUMA_NO_NODE; >>>> + best = 0; >>>> + selected = NUMA_NO_NODE; >>>> + /* select a node which contains the most cpu of cpumask */ >>>> + for_each_node_state(node, N_ONLINE) { >>>> + cpumask_and(&andmask, cpumask, cpumask_of_node(node)); >>>> + match = cpumask_weight(&andmask); >>>> + if (match > best) >>>> + selected = node; >>>> + } >>>> + return selected; >>>> +} >>>> + >>>> + >>>> /** >>>> * get_unbound_pool - get a worker_pool with the specified attributes >>>> * @attrs: the attributes of the worker_pool to get >>>> @@ -3467,7 +3493,6 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) >>>> { >>>> u32 hash = wqattrs_hash(attrs); >>>> struct worker_pool *pool; >>>> - int node; >>>> >>>> lockdep_assert_held(&wq_pool_mutex); >>>> >>>> @@ -3492,17 +3517,7 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) >>>> * 'struct workqueue_attrs' comments for detail. >>>> */ >>>> pool->attrs->no_numa = false; >>>> - >>>> - /* if cpumask is contained inside a NUMA node, we belong to that node */ >>>> - if (wq_numa_enabled) { >>>> - for_each_node(node) { >>>> - if (cpumask_subset(pool->attrs->cpumask, >>>> - wq_numa_possible_cpumask[node])) { >>>> - pool->node = node; >>>> - break; >>>> - } >>>> - } >>>> - } >>>> + pool->node = pool_detect_best_node(pool->attrs->cpumask); >>>> >>>> if (worker_pool_assign_id(pool) < 0) >>>> goto fail; >>>> @@ -4567,7 +4582,7 @@ static int workqueue_cpu_up_callback(struct notifier_block *nfb, >>>> int cpu = (unsigned long)hcpu; >>>> struct worker_pool *pool; >>>> struct workqueue_struct *wq; >>>> - int pi; >>>> + int pi, node; >>>> >>>> switch (action & ~CPU_TASKS_FROZEN) { >>>> case CPU_UP_PREPARE: >>>> @@ -4583,6 +4598,16 @@ static int workqueue_cpu_up_callback(struct notifier_block *nfb, >>>> case CPU_ONLINE: >>>> mutex_lock(&wq_pool_mutex); >>>> >>>> + /* now cpu <-> node info is established, update the info. */ >>>> + if (!wq_disable_numa) { >>> >>> >>> >>>> + for_each_node_state(node, N_POSSIBLE) >>>> + cpumask_clear_cpu(cpu, >>>> + wq_numa_possible_cpumask[node]); >>> >>> The wq code try to reuse the origin pwqs/pools when the node still have cpu online. >>> these 3 lines of code will cause the origin pwqs/pools be on the road of dying, and >>> create a new set of pwqs/pools. >> >> because the result of wq_calc_node_cpumask() changes ? > > Yes. > >> Do you mean some comment should be added here ? or explaination for your reply for [3/4] ? > > this fix [4/4] breaks the original design. > I'm sorry that I can't understand what this patch breaks. Do you mean it's better to work with broken wq_numa_possible_cpumask ? I guess removing wq_numa_possible_mask entirely may be the best way byusing online_mask of the node. Thanks, -Kame -- 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/