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workqueue: destroy worker directly in the idle timeout handler 

Since destroy_worker() doesn't need to sleep nor require manager_mutex,
destroy_worker() can be directly called in the idle timeout
handler, it helps us remove POOL_MANAGE_WORKERS and
maybe_destroy_worker() and simplify the manage_workers()

After POOL_MANAGE_WORKERS is removed, worker_thread() doesn't
need to test whether it needs to manage after processed works.
So we can remove the test branch.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
This commit is contained in:
Lai Jiangshan 2014-05-20 17:46:30 +08:00 committed by Tejun Heo
parent 60f5a4bcf8
commit 3347fc9f36
1 changed files with 5 additions and 62 deletions
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67
kernel/workqueue.c
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@ -68,7 +68,6 @@ enum {
* manager_mutex to avoid changing binding state while
* create_worker() is in progress.
*/
POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
POOL_FREEZING = 1 << 3, /* freeze in progress */
@ -752,13 +751,6 @@ static bool need_to_create_worker(struct worker_pool *pool)
return need_more_worker(pool) && !may_start_working(pool);
}
/* Do I need to be the manager? */
static bool need_to_manage_workers(struct worker_pool *pool)
{
return need_to_create_worker(pool) ||
(pool->flags & POOL_MANAGE_WORKERS);
}
/* Do we have too many workers and should some go away? */
static bool too_many_workers(struct worker_pool *pool)
{
@ -1868,7 +1860,7 @@ static void idle_worker_timeout(unsigned long __pool)
spin_lock_irq(&pool->lock);
if (too_many_workers(pool)) {
while (too_many_workers(pool)) {
struct worker *worker;
unsigned long expires;
@ -1876,13 +1868,12 @@ static void idle_worker_timeout(unsigned long __pool)
worker = list_entry(pool->idle_list.prev, struct worker, entry);
expires = worker->last_active + IDLE_WORKER_TIMEOUT;
if (time_before(jiffies, expires))
if (time_before(jiffies, expires)) {
mod_timer(&pool->idle_timer, expires);
else {
/* it's been idle for too long, wake up manager */
pool->flags |= POOL_MANAGE_WORKERS;
wake_up_worker(pool);
break;
}
destroy_worker(worker);
}
spin_unlock_irq(&pool->lock);
@ -2000,44 +1991,6 @@ restart:
return true;
}
/**
* maybe_destroy_worker - destroy workers which have been idle for a while
* @pool: pool to destroy workers for
*
* Destroy @pool workers which have been idle for longer than
* IDLE_WORKER_TIMEOUT.
*
* LOCKING:
* spin_lock_irq(pool->lock) which may be released and regrabbed
* multiple times. Called only from manager.
*
* Return:
* %false if no action was taken and pool->lock stayed locked, %true
* otherwise.
*/
static bool maybe_destroy_workers(struct worker_pool *pool)
{
bool ret = false;
while (too_many_workers(pool)) {
struct worker *worker;
unsigned long expires;
worker = list_entry(pool->idle_list.prev, struct worker, entry);
expires = worker->last_active + IDLE_WORKER_TIMEOUT;
if (time_before(jiffies, expires)) {
mod_timer(&pool->idle_timer, expires);
break;
}
destroy_worker(worker);
ret = true;
}
return ret;
}
/**
* manage_workers - manage worker pool
* @worker: self
@ -2101,13 +2054,6 @@ static bool manage_workers(struct worker *worker)
ret = true;
}
pool->flags &= ~POOL_MANAGE_WORKERS;
/*
* Destroy and then create so that may_start_working() is true
* on return.
*/
ret |= maybe_destroy_workers(pool);
ret |= maybe_create_worker(pool);
mutex_unlock(&pool->manager_mutex);
@ -2349,9 +2295,6 @@ recheck:
worker_set_flags(worker, WORKER_PREP, false);
sleep:
if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker))
goto recheck;
/*
* pool->lock is held and there's no work to process and no need to
* manage, sleep. Workers are woken up only while holding