If the device does not respond to a request for a long time,
then control vq polling elevates CPU utilization, a problem that
exacerbates with more command requests.
Enabling control vq's irq is advantageous for the guest, and
this still doesn't support concurrent requests.
Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
Signed-off-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>
---
drivers/net/virtio_net.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 0f872936d6ed..823a9dca51c1 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -372,6 +372,8 @@ struct virtio_net_ctrl_rss {
struct control_buf {
struct virtio_net_ctrl_hdr hdr;
virtio_net_ctrl_ack status;
+ /* Wait for the device to complete the cvq request. */
+ struct completion completion;
};
struct virtnet_info {
@@ -664,6 +666,13 @@ static bool virtqueue_napi_complete(struct napi_struct *napi,
return false;
}
+static void virtnet_cvq_done(struct virtqueue *cvq)
+{
+ struct virtnet_info *vi = cvq->vdev->priv;
+
+ complete(&vi->ctrl->completion);
+}
+
static void skb_xmit_done(struct virtqueue *vq)
{
struct virtnet_info *vi = vq->vdev->priv;
@@ -2723,14 +2732,8 @@ static bool virtnet_send_command_reply(struct virtnet_info *vi,
if (unlikely(!virtqueue_kick(vi->cvq)))
goto unlock;
- /* Spin for a response, the kick causes an ioport write, trapping
- * into the hypervisor, so the request should be handled immediately.
- */
- while (!virtqueue_get_buf(vi->cvq, &tmp) &&
- !virtqueue_is_broken(vi->cvq)) {
- cond_resched();
- cpu_relax();
- }
+ wait_for_completion(&vi->ctrl->completion);
+ virtqueue_get_buf(vi->cvq, &tmp);
unlock:
mutex_unlock(&vi->cvq_lock);
@@ -5314,7 +5317,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
/* Parameters for control virtqueue, if any */
if (vi->has_cvq) {
- callbacks[total_vqs - 1] = NULL;
+ callbacks[total_vqs - 1] = virtnet_cvq_done;
names[total_vqs - 1] = "control";
}
@@ -5834,6 +5837,7 @@ static int virtnet_probe(struct virtio_device *vdev)
if (vi->has_rss || vi->has_rss_hash_report)
virtnet_init_default_rss(vi);
+ init_completion(&vi->ctrl->completion);
enable_rx_mode_work(vi);
/* serialize netdev register + virtio_device_ready() with ndo_open() */
--
2.32.0.3.g01195cf9f
