virtio-balloon: improve update_balloon_size_func

wei-w-wang · mstsirkin · commit 53e946cb347e · 2019-03-06T11:19:33.000-05:00
There is no need to update the balloon actual register when there is no
ballooning request. This patch avoids update_balloon_size when diff is 0.

Signed-off-by: Wei Wang &lt;wei.w.wang@intel.com&gt;
Reviewed-by: Cornelia Huck &lt;cohuck@redhat.com&gt;
Reviewed-by: Halil Pasic &lt;pasic@linux.ibm.com&gt;
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
@@ -457,9 +457,12 @@ static void update_balloon_size_func(struct work_struct *work)
 			  update_balloon_size_work);
 	diff = towards_target(vb);
 
+	if (!diff)
+		return;
+
 	if (diff > 0)
 		diff -= fill_balloon(vb, diff);
-	else if (diff < 0)
+	else
 		diff += leak_balloon(vb, -diff);
 	update_balloon_size(vb);
 
