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Subject[PATCH 7/9] drbd: Improve asender performance
Date
From: Lars Ellenberg <lars@linbit.com>

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>
---
drivers/block/drbd/drbd_receiver.c | 6 ++++++
drivers/block/drbd/drbd_worker.c | 11 +----------
2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 3ae769e..6960fb0 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 3b74f08..3ed2d87 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;

--
1.9.1


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