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Commit 729e8b87 authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Jens Axboe
Browse files

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: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent abde9cc6

drivers/block/drbd/drbd_worker.c

+4 −6
Original line number Diff line number Diff line
@@ -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);
@@ -2130,12 +2128,12 @@ 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);

		}

		} else

			dequeue_work_batch(&connection->sender_work, &work_list);

	} while (!list_empty(&work_list) || test_bit(DEVICE_WORK_PENDING, &connection->flags));