Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751678AbaLODbs (ORCPT ); Sun, 14 Dec 2014 22:31:48 -0500 Received: from cn.fujitsu.com ([59.151.112.132]:29854 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751260AbaLODbp (ORCPT ); Sun, 14 Dec 2014 22:31:45 -0500 X-IronPort-AV: E=Sophos;i="5.04,848,1406563200"; d="scan'208";a="45149831" Message-ID: <548E56DB.7090803@cn.fujitsu.com> Date: Mon, 15 Dec 2014 11:34:51 +0800 From: Lai Jiangshan User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc14 Thunderbird/3.1.4 MIME-Version: 1.0 To: Kamezawa Hiroyuki 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> <548E4DBF.7090406@jp.fujitsu.com> In-Reply-To: <548E4DBF.7090406@jp.fujitsu.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.226.103] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/15/2014 10:55 AM, Kamezawa Hiroyuki wrote: > (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. the pwqs/pools should be kept if the node still have cpu online. -- 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/