[PATCH 04/10 V2] workqueue: destroy worker directly in the idle timeout handler

Lai Jiangshan
2014-05-12T06:52:37Z

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>
---
kernel/workqueue.c | 69 ++++------------------------------------------------
1 files changed, 5 insertions(+), 64 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 465e751..95695c3 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -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)
{
@@ -1867,8 +1859,7 @@ static void idle_worker_timeout(unsigned long __pool)
struct worker_pool *pool = (void *)__pool;

spin_lock_irq(&pool->lock);
-
- if (too_many_workers(pool)) {
+ while (too_many_workers(pool)) {
struct worker *worker;
unsigned long expires;

@@ -1876,15 +1867,13 @@ 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);
}

@@ -2001,44 +1990,6 @@ restart:
}

/**
- * 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 +2052,6 @@ 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 +2293,6 @@ 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
--
1.7.4.4