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authorLars Ellenberg <lars.ellenberg@linbit.com>2014-09-11 14:29:12 +0200
committerJens Axboe <axboe@fb.com>2014-09-11 08:41:29 -0600
commit729e8b87bac63dee09302ddffc05a7ba0e50c9ad (patch)
treef5e211f46358cec78fe411b1ddbba5f8f307991f /drivers/block/drbd/drbd_worker.c
parentabde9cc6a59cb7f07fda4c77fee2150314e423fa (diff)
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drbd: reduce lock contention in drbd_worker
The worker may now dequeue work items in batches. This should reduce lock contention during busy periods. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/block/drbd/drbd_worker.c')
-rw-r--r--drivers/block/drbd/drbd_worker.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 3ed2d871272e..d2d1f97511bd 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -2026,8 +2026,6 @@ static void wait_for_work(struct drbd_connection *connection, struct list_head *
prepare_to_wait(&connection->sender_work.q_wait, &wait, TASK_INTERRUPTIBLE);
spin_lock_irq(&connection->resource->req_lock);
spin_lock(&connection->sender_work.q_lock); /* FIXME get rid of this one? */
- /* dequeue single item only,
- * we still use drbd_queue_work_front() in some places */
if (!list_empty(&connection->sender_work.q))
list_splice_tail_init(&connection->sender_work.q, work_list);
spin_unlock(&connection->sender_work.q_lock); /* FIXME get rid of this one? */
@@ -2114,7 +2112,7 @@ int drbd_worker(struct drbd_thread *thi)
if (get_t_state(thi) != RUNNING)
break;
- while (!list_empty(&work_list)) {
+ if (!list_empty(&work_list)) {
w = list_first_entry(&work_list, struct drbd_work, list);
list_del_init(&w->list);
update_worker_timing_details(connection, w->cb);
@@ -2130,13 +2128,13 @@ int drbd_worker(struct drbd_thread *thi)
update_worker_timing_details(connection, do_unqueued_work);
do_unqueued_work(connection);
}
- while (!list_empty(&work_list)) {
+ if (!list_empty(&work_list)) {
w = list_first_entry(&work_list, struct drbd_work, list);
list_del_init(&w->list);
update_worker_timing_details(connection, w->cb);
w->cb(w, 1);
- }
- dequeue_work_batch(&connection->sender_work, &work_list);
+ } else
+ dequeue_work_batch(&connection->sender_work, &work_list);
} while (!list_empty(&work_list) || test_bit(DEVICE_WORK_PENDING, &connection->flags));
rcu_read_lock();