xen-netback: process guest rx packets in batches

Instead of only placing one skb on the guest rx ring at a time, process
a batch of up-to 64.  This improves performance by ~10% in some tests.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
[re-based]
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>

diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c
index ea1473fca1182ffb220d96fcc74cc45084492147..99e64bc0a111076add2243adc2932ea779224ac9 100644 (file)
--- a/drivers/net/xen-netback/rx.c
+++ b/drivers/net/xen-netback/rx.c
@@ -395,7 +395,7 @@ static void xenvif_rx_extra_slot(struct xenvif_queue *queue,
        BUG();
 }
 
-void xenvif_rx_action(struct xenvif_queue *queue)
+void xenvif_rx_skb(struct xenvif_queue *queue)
 {
        struct xenvif_pkt_state pkt;
 
@@ -421,6 +421,19 @@ void xenvif_rx_action(struct xenvif_queue *queue)
        xenvif_rx_complete(queue, &pkt);
 }
 
+#define RX_BATCH_SIZE 64
+
+void xenvif_rx_action(struct xenvif_queue *queue)
+{
+       unsigned int work_done = 0;
+
+       while (xenvif_rx_ring_slots_available(queue) &&
+              work_done < RX_BATCH_SIZE) {
+               xenvif_rx_skb(queue);
+               work_done++;
+       }
+}
+
 static bool xenvif_rx_queue_stalled(struct xenvif_queue *queue)
 {
        RING_IDX prod, cons;