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authorOleg Nesterov <oleg@tv-sign.ru>2007-05-09 02:33:54 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-09 12:30:51 -0700
commit83c22520c51bf67529367e8237f95c03fe44e2da (patch)
treed9798e4f60551bdad0f7d8f1f1d5c69d7c4214c1 /kernel
parentedab2516a6c1752e8e5e3d55727cabf12346e5df (diff)
downloadconfigs-83c22520c51bf67529367e8237f95c03fe44e2da.tar.gz
flush_cpu_workqueue: don't flush an empty ->worklist
Now when we have ->current_work we can avoid adding a barrier and waiting for its completition when cwq's queue is empty. Note: this change is also useful if we change flush_workqueue() to also check the dead CPUs. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Gautham Shenoy <ego@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/workqueue.c25
1 files changed, 17 insertions, 8 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 5176d51bcc2..5ecf4984e38 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -404,12 +404,15 @@ static void wq_barrier_func(struct work_struct *work)
complete(&barr->done);
}
-static inline void init_wq_barrier(struct wq_barrier *barr)
+static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
+ struct wq_barrier *barr, int tail)
{
INIT_WORK(&barr->work, wq_barrier_func);
__set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
init_completion(&barr->done);
+
+ insert_work(cwq, &barr->work, tail);
}
static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
@@ -428,13 +431,20 @@ static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
preempt_disable();
} else {
struct wq_barrier barr;
+ int active = 0;
- init_wq_barrier(&barr);
- __queue_work(cwq, &barr.work);
+ spin_lock_irq(&cwq->lock);
+ if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
+ insert_wq_barrier(cwq, &barr, 1);
+ active = 1;
+ }
+ spin_unlock_irq(&cwq->lock);
- preempt_enable(); /* Can no longer touch *cwq */
- wait_for_completion(&barr.done);
- preempt_disable();
+ if (active) {
+ preempt_enable();
+ wait_for_completion(&barr.done);
+ preempt_disable();
+ }
}
}
@@ -475,8 +485,7 @@ static void wait_on_work(struct cpu_workqueue_struct *cwq,
spin_lock_irq(&cwq->lock);
if (unlikely(cwq->current_work == work)) {
- init_wq_barrier(&barr);
- insert_work(cwq, &barr.work, 0);
+ insert_wq_barrier(cwq, &barr, 0);
running = 1;
}
spin_unlock_irq(&cwq->lock);