[RFC v3 2/7] vhost_test: batch used buffer

[Guo Zhi <qtxuning1999@xxxxxxxxxxx>]

Only add to used ring when a batch of buffer have all been used.  And if
in order feature negotiated, only add the last used descriptor for a
batch of buffer.

Signed-off-by: Guo Zhi <qtxuning1999@xxxxxxxxxxx>
---
 drivers/vhost/test.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index bc8e7fb1e635..20548a5eb3de 100644
--- a/drivers/vhost/test.c
+++ b/drivers/vhost/test.c
@@ -28,6 +28,11 @@
  */
 #define VHOST_TEST_PKT_WEIGHT 256
 
+enum {
+	VHOST_TEST_FEATURES = VHOST_FEATURES |
+			      (1ULL << VIRTIO_F_IN_ORDER)
+};
+
 enum {
 	VHOST_TEST_VQ = 0,
 	VHOST_TEST_VQ_MAX = 1,
@@ -44,7 +49,7 @@ static void handle_vq(struct vhost_test *n)
 {
 	struct vhost_virtqueue *vq = &n->vqs[VHOST_TEST_VQ];
 	unsigned out, in;
-	int head;
+	int head, add = 0;
 	size_t len, total_len = 0;
 	void *private;
 
@@ -84,11 +89,14 @@ 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);
+		vq->heads[add].id = cpu_to_vhost32(vq, head);
+		vq->heads[add++].len = cpu_to_vhost32(vq, len);
 		total_len += len;
 		if (unlikely(vhost_exceeds_weight(vq, 0, total_len)))
 			break;
 	}
+	if (add)
+		vhost_add_used_and_signal_n(&n->dev, vq, vq->heads, add);
 
 	mutex_unlock(&vq->mutex);
 }
@@ -328,7 +336,7 @@ static long vhost_test_ioctl(struct file *f, unsigned int ioctl,
 			return -EFAULT;
 		return vhost_test_set_backend(n, backend.index, backend.fd);
 	case VHOST_GET_FEATURES:
-		features = VHOST_FEATURES;
+		features = VHOST_TEST_FEATURES;
 		if (copy_to_user(featurep, &features, sizeof features))
 			return -EFAULT;
 		return 0;
@@ -337,7 +345,7 @@ static long vhost_test_ioctl(struct file *f, unsigned int ioctl,
 		if (copy_from_user(&features, featurep, sizeof features))
 			return -EFAULT;
 		printk(KERN_ERR "2\n");
-		if (features & ~VHOST_FEATURES)
+		if (features & ~VHOST_TEST_FEATURES)
 			return -EOPNOTSUPP;
 		printk(KERN_ERR "3\n");
 		return vhost_test_set_features(n, features);
-- 
2.17.1