Re: [PATCH v3 23/23] vhost: add some useful trace-points

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Oct 15, 2025 at 05:58:07PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> Reviewed-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
> Reviewed-by: Raphael Norwitz <raphael.s.norwitz@gmail.com>
> ---
>  hw/virtio/trace-events | 12 ++++++++++--
>  hw/virtio/vhost.c      | 20 ++++++++++++++++++--
>  2 files changed, 28 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index aa1ffa5e94..c2529814f9 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -9,8 +9,16 @@ vhost_section(const char *name) "%s"
>  vhost_reject_section(const char *name, int d) "%s:%d"
>  vhost_iotlb_miss(void *dev, int step) "%p step %d"
>  vhost_dev_cleanup(void *dev) "%p"
> -vhost_dev_start(void *dev, const char *name, bool vrings) "%p:%s vrings:%d"
> -vhost_dev_stop(void *dev, const char *name, bool vrings) "%p:%s vrings:%d"
> +vhost_dev_start_in(void *dev, const char *name, bool vrings) "%p:%s vrings:%d"
> +vhost_dev_start_out(void *dev, const char *name) "%p:%s"
> +vhost_dev_stop_in(void *dev, const char *name, bool vrings) "%p:%s vrings:%d"
> +vhost_dev_stop_out(void *dev, const char *name) "%p:%s"
> +vhost_virtque_start_in(void *dev, const char *name, int idx) "%p:%s %d"
> +vhost_virtque_start_out(void *dev, const char *name, int idx) "%p:%s %d"
> +vhost_virtque_stop_in(void *dev, const char *name, int idx) "%p:%s %d"
> +vhost_virtque_stop_out(void *dev, const char *name, int idx) "%p:%s %d"

virtqueue_ not virtque_

> +vhost_dev_init_in(void *dev) "%p"
> +vhost_dev_init_out(void *dev) "%p"
>  
>  
>  # vhost-user.c
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index fb5c4ba1ca..7ba90c24db 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1333,6 +1333,8 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
>      };
>      struct VirtQueue *vvq = virtio_get_queue(vdev, idx);
>  
> +    trace_vhost_virtque_start_in(dev, vdev->name, idx);
> +

should be "virtqueue"

>      r = vhost_vrings_map(dev, vdev, vq, idx);
>      if (r <= 0) {
>          return r;
> @@ -1394,6 +1396,8 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
>          }
>      }
>  
> +    trace_vhost_virtque_start_out(dev, vdev->name, idx);
> +


same


>      return 0;
>  
>  fail:
> @@ -1412,6 +1416,8 @@ static int do_vhost_virtqueue_stop(struct vhost_dev *dev,
>      };
>      int r = 0;
>  
> +    trace_vhost_virtque_stop_in(dev, vdev->name, idx);
> +

same

>      if (virtio_queue_get_desc_addr(vdev, idx) == 0) {
>          /* Don't stop the virtqueue which might have not been started */
>          return 0;
> @@ -1445,6 +1451,8 @@ static int do_vhost_virtqueue_stop(struct vhost_dev *dev,
>      }
>  
>      vhost_vrings_unmap(dev, vq, true);
> +
> +    trace_vhost_virtque_stop_out(dev, vdev->name, idx);

same

>      return r;
>  }
>  
> @@ -1616,6 +1624,8 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
>  {
>      int i, r, n_initialized_vqs = 0;
>  
> +    trace_vhost_dev_init_in(hdev);
> +
>      hdev->vdev = NULL;
>      hdev->migration_blocker = NULL;
>  
> @@ -1700,6 +1710,8 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
>          goto fail;
>      }
>  
> +    trace_vhost_dev_init_out(hdev);
> +
>      return 0;
>  
>  fail:
> @@ -2048,7 +2060,7 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
>      /* should only be called after backend is connected */
>      assert(hdev->vhost_ops);
>  
> -    trace_vhost_dev_start(hdev, vdev->name, vrings);
> +    trace_vhost_dev_start_in(hdev, vdev->name, vrings);
>  
>      vdev->vhost_started = true;
>      hdev->started = true;
> @@ -2133,6 +2145,8 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
>          }
>      }
>      vhost_start_config_intr(hdev);
> +
> +    trace_vhost_dev_start_out(hdev, vdev->name);
>      return 0;
>  fail_iotlb:
>      if (vhost_dev_has_iommu(hdev) &&
> @@ -2182,7 +2196,7 @@ static int do_vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev,
>      event_notifier_cleanup(
>          &hdev->vqs[VHOST_QUEUE_NUM_CONFIG_INR].masked_config_notifier);
>  
> -    trace_vhost_dev_stop(hdev, vdev->name, vrings);
> +    trace_vhost_dev_stop_in(hdev, vdev->name, vrings);
>  
>      if (hdev->vhost_ops->vhost_dev_start) {
>          hdev->vhost_ops->vhost_dev_start(hdev, false);
> @@ -2212,6 +2226,8 @@ static int do_vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev,
>      hdev->started = false;
>      vdev->vhost_started = false;
>      hdev->vdev = NULL;
> +
> +    trace_vhost_dev_stop_out(hdev, vdev->name);
>      return rc;
>  }
>  
> -- 
> 2.48.1