Commit 4ce62e9e authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: introduce NR_WORKER_POOLS and for_each_worker_pool() 



Introduce NR_WORKER_POOLS and for_each_worker_pool() and convert code
paths which need to manipulate all pools in a gcwq to use them.
NR_WORKER_POOLS is currently one and for_each_worker_pool() iterates
over only @gcwq->pool.

Note that nr_running is per-pool property and converted to an array
with NR_WORKER_POOLS elements and renamed to pool_nr_running.  Note
that get_pool_nr_running() currently assumes 0 index.  The next patch
will make use of non-zero index.

The changes in this patch are mechanical and don't caues any
functional difference.  This is to prepare for multiple pools per
gcwq.

v2: nr_running indexing bug in get_pool_nr_running() fixed.

v3: Pointer to array is stupid.  Don't use it in get_pool_nr_running()
    as suggested by Linus.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
parent 11ebea50

kernel/workqueue.c

+153 −70
Original line number Diff line number Diff line
@@ -74,6 +74,8 @@ enum { 
	TRUSTEE_RELEASE		= 3,		/* release workers */

	TRUSTEE_DONE		= 4,		/* trustee is done */



	NR_WORKER_POOLS		= 1,		/* # worker pools per gcwq */



	BUSY_WORKER_HASH_ORDER	= 6,		/* 64 pointers */

	BUSY_WORKER_HASH_SIZE	= 1 << BUSY_WORKER_HASH_ORDER,

	BUSY_WORKER_HASH_MASK	= BUSY_WORKER_HASH_SIZE - 1,
@@ -274,6 +276,9 @@ EXPORT_SYMBOL_GPL(system_nrt_freezable_wq); 
#define CREATE_TRACE_POINTS

#include <trace/events/workqueue.h>



#define for_each_worker_pool(pool, gcwq)				\

	for ((pool) = &(gcwq)->pool; (pool); (pool) = NULL)



#define for_each_busy_worker(worker, i, pos, gcwq)			\

	for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)			\

		hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
@@ -454,7 +459,7 @@ static bool workqueue_freezing; /* W: have wqs started freezing? */ 
 * try_to_wake_up().  Put it in a separate cacheline.

 */

static DEFINE_PER_CPU(struct global_cwq, global_cwq);

static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running);

static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, pool_nr_running[NR_WORKER_POOLS]);



/*

 * Global cpu workqueue and nr_running counter for unbound gcwq.  The
@@ -462,7 +467,9 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); 
 * workers have WORKER_UNBOUND set.

 */

static struct global_cwq unbound_global_cwq;

static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0);	/* always 0 */

static atomic_t unbound_pool_nr_running[NR_WORKER_POOLS] = {

	[0 ... NR_WORKER_POOLS - 1]	= ATOMIC_INIT(0),	/* always 0 */

};



static int worker_thread(void *__worker);
@@ -477,11 +484,12 @@ static struct global_cwq *get_gcwq(unsigned int cpu) 
static atomic_t *get_pool_nr_running(struct worker_pool *pool)

{

	int cpu = pool->gcwq->cpu;

	int idx = 0;



	if (cpu != WORK_CPU_UNBOUND)

		return &per_cpu(gcwq_nr_running, cpu);

		return &per_cpu(pool_nr_running, cpu)[idx];

	else

		return &unbound_gcwq_nr_running;

		return &unbound_pool_nr_running[idx];

}



static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
@@ -3345,9 +3353,30 @@ EXPORT_SYMBOL_GPL(work_busy); 
	__ret1 < 0 ? -1 : 0;						\

})



static bool gcwq_is_managing_workers(struct global_cwq *gcwq)

{

	struct worker_pool *pool;



	for_each_worker_pool(pool, gcwq)

		if (pool->flags & POOL_MANAGING_WORKERS)

			return true;

	return false;

}



static bool gcwq_has_idle_workers(struct global_cwq *gcwq)

{

	struct worker_pool *pool;



	for_each_worker_pool(pool, gcwq)

		if (!list_empty(&pool->idle_list))

			return true;

	return false;

}



static int __cpuinit trustee_thread(void *__gcwq)

{

	struct global_cwq *gcwq = __gcwq;

	struct worker_pool *pool;

	struct worker *worker;

	struct work_struct *work;

	struct hlist_node *pos;
@@ -3363,13 +3392,15 @@ static int __cpuinit trustee_thread(void *__gcwq) 
	 * cancelled.

	 */

	BUG_ON(gcwq->cpu != smp_processor_id());

	rc = trustee_wait_event(!(gcwq->pool.flags & POOL_MANAGING_WORKERS));

	rc = trustee_wait_event(!gcwq_is_managing_workers(gcwq));

	BUG_ON(rc < 0);



	gcwq->pool.flags |= POOL_MANAGING_WORKERS;

	for_each_worker_pool(pool, gcwq) {

		pool->flags |= POOL_MANAGING_WORKERS;



	list_for_each_entry(worker, &gcwq->pool.idle_list, entry)

		list_for_each_entry(worker, &pool->idle_list, entry)

			worker->flags |= WORKER_ROGUE;

	}



	for_each_busy_worker(worker, i, pos, gcwq)

		worker->flags |= WORKER_ROGUE;
@@ -3390,10 +3421,12 @@ static int __cpuinit trustee_thread(void *__gcwq) 
	 * keep_working() are always true as long as the worklist is

	 * not empty.

	 */

	atomic_set(get_pool_nr_running(&gcwq->pool), 0);

	for_each_worker_pool(pool, gcwq)

		atomic_set(get_pool_nr_running(pool), 0);



	spin_unlock_irq(&gcwq->lock);

	del_timer_sync(&gcwq->pool.idle_timer);

	for_each_worker_pool(pool, gcwq)

		del_timer_sync(&pool->idle_timer);

	spin_lock_irq(&gcwq->lock);



	/*
@@ -3415,31 +3448,40 @@ static int __cpuinit trustee_thread(void *__gcwq) 
	 * may be frozen works in freezable cwqs.  Don't declare

	 * completion while frozen.

	 */

	while (gcwq->pool.nr_workers != gcwq->pool.nr_idle ||

	       gcwq->flags & GCWQ_FREEZING ||

	       gcwq->trustee_state == TRUSTEE_IN_CHARGE) {

	while (true) {

		bool busy = false;



		for_each_worker_pool(pool, gcwq)

			busy |= pool->nr_workers != pool->nr_idle;



		if (!busy && !(gcwq->flags & GCWQ_FREEZING) &&

		    gcwq->trustee_state != TRUSTEE_IN_CHARGE)

			break;



		for_each_worker_pool(pool, gcwq) {

			int nr_works = 0;



		list_for_each_entry(work, &gcwq->pool.worklist, entry) {

			list_for_each_entry(work, &pool->worklist, entry) {

				send_mayday(work);

				nr_works++;

			}



		list_for_each_entry(worker, &gcwq->pool.idle_list, entry) {

			list_for_each_entry(worker, &pool->idle_list, entry) {

				if (!nr_works--)

					break;

				wake_up_process(worker->task);

			}



		if (need_to_create_worker(&gcwq->pool)) {

			if (need_to_create_worker(pool)) {

				spin_unlock_irq(&gcwq->lock);

			worker = create_worker(&gcwq->pool, false);

				worker = create_worker(pool, false);

				spin_lock_irq(&gcwq->lock);

				if (worker) {

					worker->flags |= WORKER_ROGUE;

					start_worker(worker);

				}

			}

		}



		/* give a breather */

		if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0)
@@ -3452,11 +3494,18 @@ static int __cpuinit trustee_thread(void *__gcwq) 
	 * all workers till we're canceled.

	 */

	do {

		rc = trustee_wait_event(!list_empty(&gcwq->pool.idle_list));

		while (!list_empty(&gcwq->pool.idle_list))

			destroy_worker(list_first_entry(&gcwq->pool.idle_list,

							struct worker, entry));

	} while (gcwq->pool.nr_workers && rc >= 0);

		rc = trustee_wait_event(gcwq_has_idle_workers(gcwq));



		i = 0;

		for_each_worker_pool(pool, gcwq) {

			while (!list_empty(&pool->idle_list)) {

				worker = list_first_entry(&pool->idle_list,

							  struct worker, entry);

				destroy_worker(worker);

			}

			i |= pool->nr_workers;

		}

	} while (i && rc >= 0);



	/*

	 * At this point, either draining has completed and no worker
@@ -3465,7 +3514,8 @@ static int __cpuinit trustee_thread(void *__gcwq) 
	 * Tell the remaining busy ones to rebind once it finishes the

	 * currently scheduled works by scheduling the rebind_work.

	 */

	WARN_ON(!list_empty(&gcwq->pool.idle_list));

	for_each_worker_pool(pool, gcwq)

		WARN_ON(!list_empty(&pool->idle_list));



	for_each_busy_worker(worker, i, pos, gcwq) {

		struct work_struct *rebind_work = &worker->rebind_work;
@@ -3490,7 +3540,8 @@ static int __cpuinit trustee_thread(void *__gcwq) 
	}



	/* relinquish manager role */

	gcwq->pool.flags &= ~POOL_MANAGING_WORKERS;

	for_each_worker_pool(pool, gcwq)

		pool->flags &= ~POOL_MANAGING_WORKERS;



	/* notify completion */

	gcwq->trustee = NULL;
@@ -3532,8 +3583,10 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 
	unsigned int cpu = (unsigned long)hcpu;

	struct global_cwq *gcwq = get_gcwq(cpu);

	struct task_struct *new_trustee = NULL;

	struct worker *uninitialized_var(new_worker);

	struct worker *new_workers[NR_WORKER_POOLS] = { };

	struct worker_pool *pool;

	unsigned long flags;

	int i;



	action &= ~CPU_TASKS_FROZEN;
@@ -3546,12 +3599,12 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 
		kthread_bind(new_trustee, cpu);

		/* fall through */

	case CPU_UP_PREPARE:

		BUG_ON(gcwq->pool.first_idle);

		new_worker = create_worker(&gcwq->pool, false);

		if (!new_worker) {

			if (new_trustee)

				kthread_stop(new_trustee);

			return NOTIFY_BAD;

		i = 0;

		for_each_worker_pool(pool, gcwq) {

			BUG_ON(pool->first_idle);

			new_workers[i] = create_worker(pool, false);

			if (!new_workers[i++])

				goto err_destroy;

		}

	}
@@ -3568,8 +3621,11 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 
		wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE);

		/* fall through */

	case CPU_UP_PREPARE:

		BUG_ON(gcwq->pool.first_idle);

		gcwq->pool.first_idle = new_worker;

		i = 0;

		for_each_worker_pool(pool, gcwq) {

			BUG_ON(pool->first_idle);

			pool->first_idle = new_workers[i++];

		}

		break;



	case CPU_DYING:
@@ -3586,8 +3642,10 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 
		gcwq->trustee_state = TRUSTEE_BUTCHER;

		/* fall through */

	case CPU_UP_CANCELED:

		destroy_worker(gcwq->pool.first_idle);

		gcwq->pool.first_idle = NULL;

		for_each_worker_pool(pool, gcwq) {

			destroy_worker(pool->first_idle);

			pool->first_idle = NULL;

		}

		break;



	case CPU_DOWN_FAILED:
@@ -3604,18 +3662,32 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 
		 * Put the first_idle in and request a real manager to

		 * take a look.

		 */

		for_each_worker_pool(pool, gcwq) {

			spin_unlock_irq(&gcwq->lock);

		kthread_bind(gcwq->pool.first_idle->task, cpu);

			kthread_bind(pool->first_idle->task, cpu);

			spin_lock_irq(&gcwq->lock);

		gcwq->pool.flags |= POOL_MANAGE_WORKERS;

		start_worker(gcwq->pool.first_idle);

		gcwq->pool.first_idle = NULL;

			pool->flags |= POOL_MANAGE_WORKERS;

			start_worker(pool->first_idle);

			pool->first_idle = NULL;

		}

		break;

	}



	spin_unlock_irqrestore(&gcwq->lock, flags);



	return notifier_from_errno(0);



err_destroy:

	if (new_trustee)

		kthread_stop(new_trustee);



	spin_lock_irqsave(&gcwq->lock, flags);

	for (i = 0; i < NR_WORKER_POOLS; i++)

		if (new_workers[i])

			destroy_worker(new_workers[i]);

	spin_unlock_irqrestore(&gcwq->lock, flags);



	return NOTIFY_BAD;

}



#ifdef CONFIG_SMP
@@ -3774,6 +3846,7 @@ void thaw_workqueues(void) 


	for_each_gcwq_cpu(cpu) {

		struct global_cwq *gcwq = get_gcwq(cpu);

		struct worker_pool *pool;

		struct workqueue_struct *wq;



		spin_lock_irq(&gcwq->lock);
@@ -3795,7 +3868,8 @@ void thaw_workqueues(void) 
				cwq_activate_first_delayed(cwq);

		}



		wake_up_worker(&gcwq->pool);

		for_each_worker_pool(pool, gcwq)

			wake_up_worker(pool);



		spin_unlock_irq(&gcwq->lock);

	}
@@ -3816,25 +3890,29 @@ static int __init init_workqueues(void) 
	/* initialize gcwqs */

	for_each_gcwq_cpu(cpu) {

		struct global_cwq *gcwq = get_gcwq(cpu);

		struct worker_pool *pool;



		spin_lock_init(&gcwq->lock);

		gcwq->pool.gcwq = gcwq;

		INIT_LIST_HEAD(&gcwq->pool.worklist);

		gcwq->cpu = cpu;

		gcwq->flags |= GCWQ_DISASSOCIATED;



		INIT_LIST_HEAD(&gcwq->pool.idle_list);

		for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)

			INIT_HLIST_HEAD(&gcwq->busy_hash[i]);



		init_timer_deferrable(&gcwq->pool.idle_timer);

		gcwq->pool.idle_timer.function = idle_worker_timeout;

		gcwq->pool.idle_timer.data = (unsigned long)&gcwq->pool;

		for_each_worker_pool(pool, gcwq) {

			pool->gcwq = gcwq;

			INIT_LIST_HEAD(&pool->worklist);

			INIT_LIST_HEAD(&pool->idle_list);



			init_timer_deferrable(&pool->idle_timer);

			pool->idle_timer.function = idle_worker_timeout;

			pool->idle_timer.data = (unsigned long)pool;



		setup_timer(&gcwq->pool.mayday_timer, gcwq_mayday_timeout,

			    (unsigned long)&gcwq->pool);

			setup_timer(&pool->mayday_timer, gcwq_mayday_timeout,

				    (unsigned long)pool);



		ida_init(&gcwq->pool.worker_ida);

			ida_init(&pool->worker_ida);

		}



		gcwq->trustee_state = TRUSTEE_DONE;

		init_waitqueue_head(&gcwq->trustee_wait);
@@ -3843,16 +3921,21 @@ static int __init init_workqueues(void) 
	/* create the initial worker */

	for_each_online_gcwq_cpu(cpu) {

		struct global_cwq *gcwq = get_gcwq(cpu);

		struct worker *worker;

		struct worker_pool *pool;



		if (cpu != WORK_CPU_UNBOUND)

			gcwq->flags &= ~GCWQ_DISASSOCIATED;

		worker = create_worker(&gcwq->pool, true);



		for_each_worker_pool(pool, gcwq) {

			struct worker *worker;



			worker = create_worker(pool, true);

			BUG_ON(!worker);

			spin_lock_irq(&gcwq->lock);

			start_worker(worker);

			spin_unlock_irq(&gcwq->lock);

		}

	}



	system_wq = alloc_workqueue("events", 0, 0);

	system_long_wq = alloc_workqueue("events_long", 0, 0);

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