xen-netback: Aggregate TX unmap operations

Unmapping causes TLB flushing, therefore we should make it in the largest
possible batches. However we shouldn't starve the guest for too long. So if
the guest has space for at least two big packets and we don't have at least a
quarter ring to unmap, delay it for at most 1 milisec.

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 9cc9f638f442..83a71ac5b93a 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -408,6 +408,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
                           .desc = i };
                 vif->grant_tx_handle[i] = NETBACK_INVALID_HANDLE;
         }
+        init_timer(&vif->dealloc_delay);
 
         /*
          * Initialise a dummy MAC address. We choose the numerically
@@ -556,6 +557,7 @@ void xenvif_disconnect(struct xenvif *vif)
         }
 
         if (vif->dealloc_task) {
+                del_timer_sync(&vif->dealloc_delay);
                 kthread_stop(vif->dealloc_task);
                 vif->dealloc_task = NULL;
         }