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Date: Wed, 14 Jan 2015 16:54:18 +0800
From: Lai Jiangshan <laijs@...fujitsu.com>
To: <linux-kernel@...r.kernel.org>
CC: Lai Jiangshan <laijs@...fujitsu.com>, Tejun Heo <tj@...nel.org>,
Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
"Gu, Zheng" <guz.fnst@...fujitsu.com>,
tangchen <tangchen@...fujitsu.com>,
Hiroyuki KAMEZAWA <kamezawa.hiroyu@...fujitsu.com>
Subject: [RFC PATCH 3/3 shit_B] workqueue: directly update attrs of pools when cpu hot[un]plug
If the "attrs" of the per-node pool is allowed to be updated,
we just directly update it and reduce the rebuild overhead and
memory-uasage. But the overhead of set_cpus_allowed_ptr() can not
be reduced yet.
Cc: Tejun Heo <tj@...nel.org>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc: "Gu, Zheng" <guz.fnst@...fujitsu.com>
Cc: tangchen <tangchen@...fujitsu.com>
Cc: Hiroyuki KAMEZAWA <kamezawa.hiroyu@...fujitsu.com>
Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
---
kernel/workqueue.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 69 insertions(+), 2 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 03ce500..53d2757 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -166,9 +166,10 @@ struct worker_pool {
struct ida worker_ida; /* worker IDs for task name */
- struct workqueue_attrs *attrs; /* I: worker attributes */
+ struct workqueue_attrs *attrs; /* A: worker attributes */
struct hlist_node hash_node; /* PL: unbound_pool_hash node */
int refcnt; /* PL: refcnt for unbound pools */
+ struct list_head unbound_pwqs; /* PL: list of pwq->unbound_pwq */
/*
* The current concurrency level. As it's likely to be accessed
@@ -202,6 +203,7 @@ struct pool_workqueue {
int max_active; /* L: max active works */
struct list_head delayed_works; /* L: delayed works */
struct list_head pwqs_node; /* WR: node on wq->pwqs */
+ struct list_head unbound_pwq; /* PL: node on pool->unbound_pwqs */
struct list_head mayday_node; /* MD: node on wq->maydays */
/*
@@ -3554,6 +3556,7 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
mutex_unlock(&wq->mutex);
mutex_lock(&wq_pool_mutex);
+ list_del(&pwq->unbound_pwq);
put_unbound_pool(pool);
mutex_unlock(&wq_pool_mutex);
@@ -3674,6 +3677,7 @@ static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq,
}
init_pwq(pwq, wq, pool);
+ list_add(&pwq->unbound_pwq, &pool->unbound_pwqs);
return pwq;
}
@@ -3683,6 +3687,7 @@ static void free_unbound_pwq(struct pool_workqueue *pwq)
lockdep_assert_held(&wq_pool_mutex);
if (pwq) {
+ list_del(&pwq->unbound_pwq);
put_unbound_pool(pwq->pool);
kmem_cache_free(pwq_cache, pwq);
}
@@ -3869,6 +3874,58 @@ enomem:
}
/**
+ * pool_update_unbound_numa - update NUMA affinity of a pool for CPU hot[un]plug
+ * @pool: the target pool
+ * @cpu: the CPU coming up or going down
+ * @online: whether @cpu is coming up or going down
+ *
+ * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
+ * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
+ * @pool when allowed.
+ */
+static void pool_update_unbound_numa(struct worker_pool *pool, int cpu, bool online)
+{
+ u32 hash;
+ struct pool_workqueue *pwq;
+ struct worker *worker;
+
+ if (pool->cpu >= 0 || pool->node != cpu_to_node(cpu))
+ return; /* it must not be an unbound pool of the node */
+ if (online && cpumask_test_cpu(cpu, pool->attrs->cpumask))
+ return; /* it already has the online cpu */
+ if (!online && !cpumask_test_cpu(cpu, pool->attrs->cpumask))
+ return; /* it doesn't has the cpu to be removed */
+ if (!online && cpumask_weight(pool->attrs->cpumask) == 1)
+ return; /* the last cpu can't be removed from the pool */
+
+ /* It is called from CPU hot[un]plug, wq->unbound_attrs is stable */
+ list_for_each_entry(pwq, &pool->unbound_pwqs, unbound_pwq) {
+ if (wqattrs_equal(pool->attrs, pwq->wq->unbound_attrs))
+ return; /* the pool serves for at least a default pwq */
+ if (online && !cpumask_test_cpu(cpu, pwq->wq->unbound_attrs->cpumask))
+ return; /* this wq doesn't allow us to add the cpu */
+ }
+
+ /* OK, all pwqs allows us to update the pool directly, let's go */
+ mutex_lock(&pool->attach_mutex);
+ if (online)
+ cpumask_set_cpu(cpu, pool->attrs->cpumask);
+ else
+ cpumask_clear_cpu(cpu, pool->attrs->cpumask);
+
+ /* rehash */
+ hash = wqattrs_hash(pool->attrs);
+ hash_del(&pool->hash_node);
+ hash_add(unbound_pool_hash, &pool->hash_node, hash);
+
+ /* update worker's cpumask */
+ for_each_pool_worker(worker, pool)
+ WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
+ pool->attrs->cpumask) < 0);
+ mutex_unlock(&pool->attach_mutex);
+}
+
+/**
* wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
* @wq: the target workqueue
* @cpu: the CPU coming up or going down
@@ -4598,6 +4655,8 @@ static int workqueue_cpu_up_callback(struct notifier_block *nfb,
restore_unbound_workers_cpumask(pool, cpu);
mutex_unlock(&pool->attach_mutex);
+
+ pool_update_unbound_numa(pool, cpu, true);
}
/* update NUMA affinity of unbound workqueues */
@@ -4621,6 +4680,8 @@ static int workqueue_cpu_down_callback(struct notifier_block *nfb,
int cpu = (unsigned long)hcpu;
struct work_struct unbind_work;
struct workqueue_struct *wq;
+ struct worker_pool *pool;
+ int pi;
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_PREPARE:
@@ -4628,10 +4689,16 @@ static int workqueue_cpu_down_callback(struct notifier_block *nfb,
INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn);
queue_work_on(cpu, system_highpri_wq, &unbind_work);
- /* update NUMA affinity of unbound workqueues */
mutex_lock(&wq_pool_mutex);
+
+ /* try to update NUMA affinity of unbound pool */
+ for_each_pool(pool, pi)
+ pool_update_unbound_numa(pool, cpu, false);
+
+ /* update NUMA affinity of unbound workqueues */
list_for_each_entry(wq, &workqueues, list)
wq_update_unbound_numa(wq, cpu, false);
+
mutex_unlock(&wq_pool_mutex);
/* wait for per-cpu unbinding to finish */
--
2.1.0
--
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