[Xen-devel] [4/11] [NET] front: Move rx req pushing to one spot

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

Hi:

[NET] front: Move rx req pushing to one spot

This patch moves all rx request pushing to network_alloc_rx_buffers.
This is needed to reduce churn for TSO.  More importantly, this makes
it easier to send notifications when adding rx requests which is
required for having a queue in dom0.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

Cheers,
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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--
diff -r 2ec3e15164f7 -r d398fb29e84a 
linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c      Fri Jul 07 
23:35:52 2006 +1000
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c      Fri Jul 07 
23:36:12 2006 +1000
@@ -600,14 +600,17 @@ static void network_alloc_rx_buffers(str
                        /* Could not allocate any skbuffs. Try again later. */
                        mod_timer(&np->rx_refill_timer,
                                  jiffies + (HZ/10));
-                       return;
+                       break;
                }
                __skb_queue_tail(&np->rx_batch, skb);
        }
 
        /* Is the batch large enough to be worthwhile? */
-       if (i < (np->rx_target/2))
+       if (i < (np->rx_target/2)) {
+               if (req_prod > np->rx.sring->req_prod)
+                       goto push;
                return;
+       }
 
        /* Adjust our fill target if we risked running out of buffers. */
        if (((req_prod - np->rx.sring->rsp_prod) < (np->rx_target / 4)) &&
@@ -678,6 +681,7 @@ static void network_alloc_rx_buffers(str
 
        /* Above is a suitable barrier to ensure backend will see requests. */
        np->rx.req_prod_pvt = req_prod + i;
+push:
        RING_PUSH_REQUESTS(&np->rx);
 }
 
@@ -875,7 +879,6 @@ static void xennet_move_rx_slot(struct n
        RING_GET_REQUEST(&np->rx, np->rx.req_prod_pvt)->id = new;
        RING_GET_REQUEST(&np->rx, np->rx.req_prod_pvt)->gref = ref;
        np->rx.req_prod_pvt++;
-       RING_PUSH_REQUESTS(&np->rx);
 }
 
 static int netif_poll(struct net_device *dev, int *pbudget)
@@ -1213,7 +1216,6 @@ static void network_connect(struct net_d
        }
 
        np->rx.req_prod_pvt = requeue_idx;
-       RING_PUSH_REQUESTS(&np->rx);
 
        /*
         * Step 3: All public and private state should now be sane.  Get

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