Re: [RFC 3/5] vhost_test: batch used buffer
From: Guo Zhi <hidden>
Date: 2022-08-02 02:47:56
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kvm, lkml
----- Original Message ----- From: "eperezma" <eperezma@redhat.com> To: "Guo Zhi" <redacted> Cc: "jasowang" <jasowang@redhat.com>, "sgarzare" <sgarzare@redhat.com>, "Michael Tsirkin" <mst@redhat.com>, "netdev" <redacted>, "linux-kernel" <redacted>, "kvm list" <redacted>, "virtualization" <redacted> 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 [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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