From: Jason Wang <jasowang@redhat.com>
Date: Thu, 20 Jul 2023 08:38:39 +0000 (-0400)
Subject: virtio-net: add cond_resched() to the command waiting loop
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0d197a14716481626f863d2091f4c328bf5412e3;p=linux.git

virtio-net: add cond_resched() to the command waiting loop

Adding cond_resched() to the command waiting loop for a better
co-operation with the scheduler. This allows to give CPU a breath to
run other task(workqueue) instead of busy looping when preemption is
not allowed on a device whose CVQ might be slow.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230720083839.481487-3-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
---

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 46fc86fe62df3..e709d4411810d 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2570,8 +2570,10 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
 	 * into the hypervisor, so the request should be handled immediately.
 	 */
 	while (!virtqueue_get_buf(vi->cvq, &tmp) &&
-	       !virtqueue_is_broken(vi->cvq))
+	       !virtqueue_is_broken(vi->cvq)) {
+		cond_resched();
 		cpu_relax();
+	}
 
 	return vi->ctrl->status == VIRTIO_NET_OK;
 }