Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750822AbaLOCob (ORCPT ); Sun, 14 Dec 2014 21:44:31 -0500 Received: from cn.fujitsu.com ([59.151.112.132]:13022 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1750713AbaLOCoX (ORCPT ); Sun, 14 Dec 2014 21:44:23 -0500 X-IronPort-AV: E=Sophos;i="5.04,848,1406563200"; d="scan'208";a="45147225" Message-ID: <548E4BF7.3000605@cn.fujitsu.com> Date: Mon, 15 Dec 2014 10:48:23 +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> In-Reply-To: <548E4578.3070209@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 10:20 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. > > Thanks, > -Kame > > > > > >> >>> + node = cpu_to_node(cpu); >>> + cpumask_set_cpu(cpu, wq_numa_possible_cpumask[node]); >>> + } >>> + for_each_cpu_worker_pool(pool, cpu) >>> + pool->node = cpu_to_node(cpu); >>> for_each_pool(pool, pi) { >>> mutex_lock(&pool->attach_mutex); >>> >>> @@ -4951,7 +4976,21 @@ void workqueue_register_numanode(int nid) >>> void workqueue_unregister_numanode(int nid) >>> { >>> struct workqueue_struct *wq; >>> + const struct cpumask *nodecpumask; >>> + struct worker_pool *pool; >>> + int cpu; >>> >>> + /* at this point, cpu-to-node relationship is not lost */ >>> + nodecpumask = cpumask_of_node(nid); >>> + for_each_cpu(cpu, nodecpumask) { >>> + /* >>> + * pool is allcated at boot and assumed to be persistent, >>> + * we cannot free this. >>> + * Update to be NUMA_NO_NODE. This will be fixed at ONLINE >>> + */ >>> + for_each_cpu_worker_pool(pool, cpu) >>> + pool->node = NUMA_NO_NODE; >>> + } >>> mutex_lock(&wq_pool_mutex); >>> list_for_each_entry(wq, &workqueues, list) >>> wq_release_unbound_numa(wq, nid); >> > > > . > -- 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/