xen-netfront: request Tx response events more often
Trying to batch Tx response events results in poor performance because
this delays freeing the transmitted skbs.
Instead use the standard RING_FINAL_CHECK_FOR_RESPONSES() macro to be
notified once the next Tx response is placed on the ring.
Signed-off-by: Malcolm Crossley <malcolm.crossley@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index d6abf19..96ccd4e 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -364,6 +364,7 @@
RING_IDX cons, prod;
unsigned short id;
struct sk_buff *skb;
+ bool more_to_do;
BUG_ON(!netif_carrier_ok(queue->info->netdev));
@@ -398,18 +399,8 @@
queue->tx.rsp_cons = prod;
- /*
- * Set a new event, then check for race with update of tx_cons.
- * Note that it is essential to schedule a callback, no matter
- * how few buffers are pending. Even if there is space in the
- * transmit ring, higher layers may be blocked because too much
- * data is outstanding: in such cases notification from Xen is
- * likely to be the only kick that we'll get.
- */
- queue->tx.sring->rsp_event =
- prod + ((queue->tx.sring->req_prod - prod) >> 1) + 1;
- mb(); /* update shared area */
- } while ((cons == prod) && (prod != queue->tx.sring->rsp_prod));
+ RING_FINAL_CHECK_FOR_RESPONSES(&queue->tx, more_to_do);
+ } while (more_to_do);
xennet_maybe_wake_tx(queue);
}