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Re: [PATCH v2] vhost: don't set vring call if guest notifiers is not ena
From: |
Michael S. Tsirkin |
Subject: |
Re: [PATCH v2] vhost: don't set vring call if guest notifiers is not enabled |
Date: |
Tue, 9 Apr 2024 05:32:28 -0400 |
On Mon, Apr 08, 2024 at 03:33:11PM +0800, lyx634449800 wrote:
> When conducting performance testing using testpmd in the guest os,
> it was observed that the performance was lower compared to the
> scenario of direct vfio-pci usage.
>
> In the commit 96a3d98d2cdbd897ff5ab33427aa4cfb94077665, the author
> provided a good solution. However, because the guest OS's
> driver(e.g., virtio-net pmd) may not enable the msix capability, the
> function k->query_guest_notifiers(qbus->parent) may return false,
> resulting in the expected effect not being achieved. To address this
> issue, modify the conditional statement.
>
> Signed-off-by: Yuxue Liu <yuxue.liu@jaguarmicro.com>
I tested v1 and it fails. Sent as reply on that patch.
Since all you did is tweak description and title the
problem is probably still there in v2.
> ---
> V2: Update commit description and title
>
> hw/virtio/vhost.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index f50180e60e..b972c84e67 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1266,13 +1266,15 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
> vhost_virtqueue_mask(dev, vdev, idx, false);
> }
>
> - if (k->query_guest_notifiers &&
> - k->query_guest_notifiers(qbus->parent) &&
> - virtio_queue_vector(vdev, idx) == VIRTIO_NO_VECTOR) {
> - file.fd = -1;
> - r = dev->vhost_ops->vhost_set_vring_call(dev, &file);
> - if (r) {
> - goto fail_vector;
> + if (k->query_guest_notifiers) {
> + if (!k->query_guest_notifiers(qbus->parent) ||
> + (k->query_guest_notifiers(qbus->parent) &&
> + virtio_queue_vector(vdev, idx) == VIRTIO_NO_VECTOR)) {
> + file.fd = -1;
> + r = dev->vhost_ops->vhost_set_vring_call(dev, &file);
> + if (r) {
> + goto fail_vector;
> + }
> }
> }
>
> --
> 2.43.0