----- Original Message -----
From: "eperezma" <eperezma@xxxxxxxxxx>
To: "Guo Zhi" <qtxuning1999@xxxxxxxxxxx>
Cc: "jasowang" <jasowang@xxxxxxxxxx>, "sgarzare" <sgarzare@xxxxxxxxxx>, "Michael Tsirkin" <mst@xxxxxxxxxx>, "netdev" <netdev@xxxxxxxxxxxxxxx>, "linux-kernel" <linux-kernel@xxxxxxxxxxxxxxx>, "kvm list" <kvm@xxxxxxxxxxxxxxx>, "virtualization" <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>
Sent: Friday, July 22, 2022 3:12:47 PM
Subject: Re: [RFC 3/5] vhost_test: batch used buffer
On Thu, Jul 21, 2022 at 10:44 AM Guo Zhi <qtxuning1999@xxxxxxxxxxx> wrote:
>
> Only add to used ring when a batch a buffer have all been used. And if
> in order feature negotiated, add randomness to the used buffer's order,
> test the ability of vhost to reorder batched buffer.
>
> Signed-off-by: Guo Zhi <qtxuning1999@xxxxxxxxxxx>
> ---
> drivers/vhost/test.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
> index bc8e7fb1e..1c9c40c11 100644
> --- a/drivers/vhost/test.c
> +++ b/drivers/vhost/test.c
> @@ -43,6 +43,9 @@ struct vhost_test {
> static void handle_vq(struct vhost_test *n)
> {
> struct vhost_virtqueue *vq = &n->vqs[VHOST_TEST_VQ];
> + struct vring_used_elem *heads = kmalloc(sizeof(*heads)
> + * vq->num, GFP_KERNEL);
> + int batch_idx = 0;
> unsigned out, in;
> int head;
> size_t len, total_len = 0;
> @@ -84,11 +87,21 @@ static void handle_vq(struct vhost_test *n)
> vq_err(vq, "Unexpected 0 len for TX\n");
> break;
> }
> - vhost_add_used_and_signal(&n->dev, vq, head, 0);
> + heads[batch_idx].id = cpu_to_vhost32(vq, head);
> + heads[batch_idx++].len = cpu_to_vhost32(vq, len);
> total_len += len;
> if (unlikely(vhost_exceeds_weight(vq, 0, total_len)))
> break;
> }
> + if (batch_idx) {
> + if (vhost_has_feature(vq, VIRTIO_F_IN_ORDER) && batch_idx >= 2) {
Maybe to add a module parameter to test this? Instead of trusting in
feature negotiation, "unorder_used=1" or something like that.
vhost.c:vhost_add_used_and_signal_n should support receiving buffers
in order or out of order whether F_IN_ORDER is negotiated or not.
Thanks!
> + vhost_add_used_and_signal_n(&n->dev, vq, &heads[batch_idx / 2],
> + batch_idx - batch_idx / 2);
> + vhost_add_used_and_signal_n(&n->dev, vq, heads, batch_idx / 2);
> + } else {
> + vhost_add_used_and_signal_n(&n->dev, vq, heads, batch_idx);
> + }
> + }
>
> mutex_unlock(&vq->mutex);
> }
> --
> 2.17.1
