drbd: Improve asender performance

Shorten receive path in the asender thread. Reduces CPU utilisation
of asender when receiving packets, and with that increases IOPs.

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>

2 files changed, 7 insertions, 10 deletions

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 3ae769e671e8..6960fb064731 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -5561,6 +5561,7 @@ int drbd_asender(struct drbd_thread *thi)
                  * rv <  expected: "woken" by signal during receive
                  * rv == 0       : "connection shut down by peer"
                  */
+received_more:
                 if (likely(rv > 0)) {
                         received += rv;
                         buf      += rv;
@@ -5636,6 +5637,11 @@ int drbd_asender(struct drbd_thread *thi)
                         expect   = header_size;
                         cmd      = NULL;
                 }
+                if (test_bit(SEND_PING, &connection->flags))
+                        continue;
+                rv = drbd_recv_short(connection->meta.socket, buf, expect-received, MSG_DONTWAIT);
+                if (rv > 0)
+                        goto received_more;
         }
 
         if (0) {
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 3b74f08c8b83..3ed2d871272e 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -1994,22 +1994,13 @@ static bool dequeue_work_batch(struct drbd_work_queue *queue, struct list_head *
         return !list_empty(work_list);
 }
 
-static bool dequeue_work_item(struct drbd_work_queue *queue, struct list_head *work_list)
-{
-        spin_lock_irq(&queue->q_lock);
-        if (!list_empty(&queue->q))
-                list_move(queue->q.next, work_list);
-        spin_unlock_irq(&queue->q_lock);
-        return !list_empty(work_list);
-}
-
 static void wait_for_work(struct drbd_connection *connection, struct list_head *work_list)
 {
         DEFINE_WAIT(wait);
         struct net_conf *nc;
         int uncork, cork;
 
-        dequeue_work_item(&connection->sender_work, work_list);
+        dequeue_work_batch(&connection->sender_work, work_list);
         if (!list_empty(work_list))
                 return;