[S390] qdio: speed up multicast traffic on full HiperSocket queue

If an asynchronous HiperSockets queue runs full, no further packet
can be sent. In this case the next initiative to give transmitted
skbs back to the stack is triggered only by a 10-seconds qdio timer.
This timer has been introduced for low multicast traffic scenarios
to guarantee freeing of skbs in a limited amount of time. For high
HiperSocket multicast traffic scenarios progress checking on the
outbound queue should be enforced by tasklet rescheduling.

Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/cio/qdio.h b/drivers/s390/cio/qdio.h
index c1a70985abfaf7d877fa60d4d6f72a78640cf5e9..af867731a5f4c86bedf7688b6095c32da89b721f 100644 (file)
--- a/drivers/s390/cio/qdio.h
+++ b/drivers/s390/cio/qdio.h
@@ -16,6 +16,14 @@
 #define QDIO_BUSY_BIT_GIVE_UP          2000000 /* 2 seconds = eternity */
 #define QDIO_INPUT_THRESHOLD           500     /* 500 microseconds */
 
+/*
+ * if an asynchronous HiperSockets queue runs full, the 10 seconds timer wait
+ * till next initiative to give transmitted skbs back to the stack is too long.
+ * Therefore polling is started in case of multicast queue is filled more
+ * than 50 percent.
+ */
+#define QDIO_IQDIO_POLL_LVL            65      /* HS multicast queue */
+
 enum qdio_irq_states {
        QDIO_IRQ_STATE_INACTIVE,
        QDIO_IRQ_STATE_ESTABLISHED,

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index e6eabc853422cc9320c7925099471ec04e48f44b..9307512132fe565f3ea738c7ff2401d9e7a0a552 100644 (file)
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -851,6 +851,12 @@ static void __qdio_outbound_processing(struct qdio_q *q)
        if (queue_type(q) == QDIO_IQDIO_QFMT && !multicast_outbound(q))
                return;
 
+       if ((queue_type(q) == QDIO_IQDIO_QFMT) &&
+           (atomic_read(&q->nr_buf_used)) > QDIO_IQDIO_POLL_LVL) {
+               tasklet_schedule(&q->tasklet);
+               return;
+       }
+
        if (q->u.out.pci_out_enabled)
                return;