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[PATCH net-next RFC 0/5] batched tx processing in vhost_net

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  [PATCH net-next RFC 0/5] batched tx processing in vhost_net Jason Wang <jasowang@redhat.com> - 2017-09-22 10:10 +0200
    [PATCH net-next RFC 5/5] vhost_net: basic tx virtqueue batched processing Jason Wang <jasowang@redhat.com> - 2017-09-22 10:10 +0200
    [PATCH net-next RFC 1/5] vhost: split out ring head fetching logic Jason Wang <jasowang@redhat.com> - 2017-09-22 10:10 +0200
      Re: [PATCH net-next RFC 1/5] vhost: split out ring head fetching  logic Stefan Hajnoczi <stefanha@gmail.com> - 2017-09-22 10:40 +0200
        Re: [PATCH net-next RFC 1/5] vhost: split out ring head fetching  logic Jason Wang <jasowang@redhat.com> - 2017-09-25 04:10 +0200
    Re: [PATCH net-next RFC 0/5] batched tx processing in vhost_net "Michael S. Tsirkin" <mst@redhat.com> - 2017-09-26 15:50 +0200

#1737254 — [PATCH net-next RFC 0/5] batched tx processing in vhost_net

Hi:

This series tries to implement basic tx batched processing. This is
done by prefetching descriptor indices and update used ring in a
batch. This intends to speed up used ring updating and improve the
cache utilization. Test shows about ~22% improvement in tx pss.

Please review.

Jason Wang (5):
  vhost: split out ring head fetching logic
  vhost: introduce helper to prefetch desc index
  vhost: introduce vhost_add_used_idx()
  vhost_net: rename VHOST_RX_BATCH to VHOST_NET_BATCH
  vhost_net: basic tx virtqueue batched processing

 drivers/vhost/net.c   | 221 ++++++++++++++++++++++++++++----------------------
 drivers/vhost/vhost.c | 165 +++++++++++++++++++++++++++++++------
 drivers/vhost/vhost.h |   9 ++
 3 files changed, 270 insertions(+), 125 deletions(-)

-- 
2.7.4

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#1737257 — [PATCH net-next RFC 5/5] vhost_net: basic tx virtqueue batched processing

This patch implements basic batched processing of tx virtqueue by
prefetching desc indices and updating used ring in a batch. For
non-zerocopy case, vq->heads were used for storing the prefetched
indices and updating used ring. It is also a requirement for doing
more batching on top. For zerocopy case and for simplicity, batched
processing were simply disabled by only fetching and processing one
descriptor at a time, this could be optimized in the future.

XDP_DROP (without touching skb) on tun (with Moongen in guest) with
zercopy disabled:

Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz:
Before: 3.20Mpps
After:  3.90Mpps (+22%)

No differences were seen with zerocopy enabled.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vhost/net.c   | 215 ++++++++++++++++++++++++++++----------------------
 drivers/vhost/vhost.c |   2 +-
 2 files changed, 121 insertions(+), 96 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index c89640e..c439892 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -408,27 +408,25 @@ static int vhost_net_enable_vq(struct vhost_net *n,
 	return vhost_poll_start(poll, sock->file);
 }
 
-static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
-				    struct vhost_virtqueue *vq,
-				    struct iovec iov[], unsigned int iov_size,
-				    unsigned int *out_num, unsigned int *in_num)
+static bool vhost_net_tx_avail(struct vhost_net *net,
+			       struct vhost_virtqueue *vq)
 {
 	unsigned long uninitialized_var(endtime);
-	int r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
-				  out_num, in_num, NULL, NULL);
 
-	if (r == vq->num && vq->busyloop_timeout) {
-		preempt_disable();
-		endtime = busy_clock() + vq->busyloop_timeout;
-		while (vhost_can_busy_poll(vq->dev, endtime) &&
-		       vhost_vq_avail_empty(vq->dev, vq))
-			cpu_relax();
-		preempt_enable();
-		r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
-				      out_num, in_num, NULL, NULL);
-	}
+	if (!vq->busyloop_timeout)
+		return false;
 
-	return r;
+	if (!vhost_vq_avail_empty(vq->dev, vq))
+		return true;
+
+	preempt_disable();
+	endtime = busy_clock() + vq->busyloop_timeout;
+	while (vhost_can_busy_poll(vq->dev, endtime) &&
+		vhost_vq_avail_empty(vq->dev, vq))
+		cpu_relax();
+	preempt_enable();
+
+	return !vhost_vq_avail_empty(vq->dev, vq);
 }
 
 static bool vhost_exceeds_maxpend(struct vhost_net *net)
@@ -446,8 +444,9 @@ static void handle_tx(struct vhost_net *net)
 {
 	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 	struct vhost_virtqueue *vq = &nvq->vq;
+	struct vring_used_elem used, *heads = vq->heads;
 	unsigned out, in;
-	int head;
+	int avails, head;
 	struct msghdr msg = {
 		.msg_name = NULL,
 		.msg_namelen = 0,
@@ -461,6 +460,7 @@ static void handle_tx(struct vhost_net *net)
 	struct socket *sock;
 	struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
 	bool zcopy, zcopy_used;
+	int i, batched = VHOST_NET_BATCH;
 
 	mutex_lock(&vq->mutex);
 	sock = vq->private_data;
@@ -475,6 +475,12 @@ static void handle_tx(struct vhost_net *net)
 	hdr_size = nvq->vhost_hlen;
 	zcopy = nvq->ubufs;
 
+	/* Disable zerocopy batched fetching for simplicity */
+	if (zcopy) {
+		heads = &used;
+		batched = 1;
+	}
+
 	for (;;) {
 		/* Release DMAs done buffers first */
 		if (zcopy)
@@ -486,95 +492,114 @@ static void handle_tx(struct vhost_net *net)
 		if (unlikely(vhost_exceeds_maxpend(net)))
 			break;
 
-		head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
-						ARRAY_SIZE(vq->iov),
-						&out, &in);
+		avails = vhost_prefetch_desc_indices(vq, heads, batched, !zcopy);
 		/* On error, stop handling until the next kick. */
-		if (unlikely(head < 0))
+		if (unlikely(avails < 0))
 			break;
-		/* Nothing new?  Wait for eventfd to tell us they refilled. */
-		if (head == vq->num) {
+		/* Nothing new?  Busy poll for a while or wait for
+		 * eventfd to tell us they refilled. */
+		if (!avails) {
+			if (vhost_net_tx_avail(net, vq))
+				continue;
 			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 				vhost_disable_notify(&net->dev, vq);
 				continue;
 			}
 			break;
 		}
-		if (in) {
-			vq_err(vq, "Unexpected descriptor format for TX: "
-			       "out %d, int %d\n", out, in);
-			break;
-		}
-		/* Skip header. TODO: support TSO. */
-		len = iov_length(vq->iov, out);
-		iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
-		iov_iter_advance(&msg.msg_iter, hdr_size);
-		/* Sanity check */
-		if (!msg_data_left(&msg)) {
-			vq_err(vq, "Unexpected header len for TX: "
-			       "%zd expected %zd\n",
-			       len, hdr_size);
-			break;
-		}
-		len = msg_data_left(&msg);
-
-		zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
-				   && (nvq->upend_idx + 1) % UIO_MAXIOV !=
-				      nvq->done_idx
-				   && vhost_net_tx_select_zcopy(net);
-
-		/* use msg_control to pass vhost zerocopy ubuf info to skb */
-		if (zcopy_used) {
-			struct ubuf_info *ubuf;
-			ubuf = nvq->ubuf_info + nvq->upend_idx;
-
-			vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
-			vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
-			ubuf->callback = vhost_zerocopy_callback;
-			ubuf->ctx = nvq->ubufs;
-			ubuf->desc = nvq->upend_idx;
-			refcount_set(&ubuf->refcnt, 1);
-			msg.msg_control = ubuf;
-			msg.msg_controllen = sizeof(ubuf);
-			ubufs = nvq->ubufs;
-			atomic_inc(&ubufs->refcount);
-			nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
-		} else {
-			msg.msg_control = NULL;
-			ubufs = NULL;
-		}
+		for (i = 0; i < avails; i++) {
+			head = __vhost_get_vq_desc(vq, vq->iov,
+						   ARRAY_SIZE(vq->iov),
+						   &out, &in, NULL, NULL,
+					       vhost16_to_cpu(vq, heads[i].id));
+			if (in) {
+				vq_err(vq, "Unexpected descriptor format for "
+					   "TX: out %d, int %d\n", out, in);
+				goto out;
+			}
 
-		total_len += len;
-		if (total_len < VHOST_NET_WEIGHT &&
-		    !vhost_vq_avail_empty(&net->dev, vq) &&
-		    likely(!vhost_exceeds_maxpend(net))) {
-			msg.msg_flags |= MSG_MORE;
-		} else {
-			msg.msg_flags &= ~MSG_MORE;
-		}
+			/* Skip header. TODO: support TSO. */
+			len = iov_length(vq->iov, out);
+			iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
+			iov_iter_advance(&msg.msg_iter, hdr_size);
+			/* Sanity check */
+			if (!msg_data_left(&msg)) {
+				vq_err(vq, "Unexpected header len for TX: "
+					"%zd expected %zd\n",
+					len, hdr_size);
+				goto out;
+			}
+			len = msg_data_left(&msg);
 
-		/* TODO: Check specific error and bomb out unless ENOBUFS? */
-		err = sock->ops->sendmsg(sock, &msg, len);
-		if (unlikely(err < 0)) {
+			zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
+				     && (nvq->upend_idx + 1) % UIO_MAXIOV !=
+					nvq->done_idx
+				     && vhost_net_tx_select_zcopy(net);
+
+			/* use msg_control to pass vhost zerocopy ubuf
+			 * info to skb
+			 */
 			if (zcopy_used) {
-				vhost_net_ubuf_put(ubufs);
-				nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
-					% UIO_MAXIOV;
+				struct ubuf_info *ubuf;
+				ubuf = nvq->ubuf_info + nvq->upend_idx;
+
+				vq->heads[nvq->upend_idx].id =
+					cpu_to_vhost32(vq, head);
+				vq->heads[nvq->upend_idx].len =
+					VHOST_DMA_IN_PROGRESS;
+				ubuf->callback = vhost_zerocopy_callback;
+				ubuf->ctx = nvq->ubufs;
+				ubuf->desc = nvq->upend_idx;
+				refcount_set(&ubuf->refcnt, 1);
+				msg.msg_control = ubuf;
+				msg.msg_controllen = sizeof(ubuf);
+				ubufs = nvq->ubufs;
+				atomic_inc(&ubufs->refcount);
+				nvq->upend_idx =
+					(nvq->upend_idx + 1) % UIO_MAXIOV;
+			} else {
+				msg.msg_control = NULL;
+				ubufs = NULL;
+			}
+
+			total_len += len;
+			if (total_len < VHOST_NET_WEIGHT &&
+				!vhost_vq_avail_empty(&net->dev, vq) &&
+				likely(!vhost_exceeds_maxpend(net))) {
+				msg.msg_flags |= MSG_MORE;
+			} else {
+				msg.msg_flags &= ~MSG_MORE;
+			}
+
+			/* TODO: Check specific error and bomb out
+			 * unless ENOBUFS?
+			 */
+			err = sock->ops->sendmsg(sock, &msg, len);
+			if (unlikely(err < 0)) {
+				if (zcopy_used) {
+					vhost_net_ubuf_put(ubufs);
+					nvq->upend_idx =
+				   ((unsigned)nvq->upend_idx - 1) % UIO_MAXIOV;
+				}
+				vhost_discard_vq_desc(vq, 1);
+				goto out;
+			}
+			if (err != len)
+				pr_debug("Truncated TX packet: "
+					" len %d != %zd\n", err, len);
+			if (!zcopy) {
+				vhost_add_used_idx(vq, 1);
+				vhost_signal(&net->dev, vq);
+			} else if (!zcopy_used) {
+				vhost_add_used_and_signal(&net->dev,
+							  vq, head, 0);
+			} else
+				vhost_zerocopy_signal_used(net, vq);
+			vhost_net_tx_packet(net);
+			if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
+				vhost_poll_queue(&vq->poll);
+				goto out;
 			}
-			vhost_discard_vq_desc(vq, 1);
-			break;
-		}
-		if (err != len)
-			pr_debug("Truncated TX packet: "
-				 " len %d != %zd\n", err, len);
-		if (!zcopy_used)
-			vhost_add_used_and_signal(&net->dev, vq, head, 0);
-		else
-			vhost_zerocopy_signal_used(net, vq);
-		vhost_net_tx_packet(net);
-		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
-			vhost_poll_queue(&vq->poll);
-			break;
 		}
 	}
 out:
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 6532cda..8764df5 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -392,7 +392,7 @@ static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
 		vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
 				       GFP_KERNEL);
 		vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
-		vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
+		vq->heads = kzalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
 		if (!vq->indirect || !vq->log || !vq->heads)
 			goto err_nomem;
 	}
-- 
2.7.4

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#1737258 — [PATCH net-next RFC 1/5] vhost: split out ring head fetching logic

This patch splits out ring head fetching logic and leave the
descriptor fetching and translation logic. This makes it is possible
to batch fetching the descriptor indices.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vhost/vhost.c | 75 +++++++++++++++++++++++++++++++++------------------
 drivers/vhost/vhost.h |  5 ++++
 2 files changed, 54 insertions(+), 26 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index d6dbb28..f87ec75 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1984,41 +1984,23 @@ static int get_indirect(struct vhost_virtqueue *vq,
 	return 0;
 }
 
-/* This looks in the virtqueue and for the first available buffer, and converts
- * it to an iovec for convenient access.  Since descriptors consist of some
- * number of output then some number of input descriptors, it's actually two
- * iovecs, but we pack them into one and note how many of each there were.
- *
- * This function returns the descriptor number found, or vq->num (which is
- * never a valid descriptor number) if none was found.  A negative code is
- * returned on error. */
-int vhost_get_vq_desc(struct vhost_virtqueue *vq,
-		      struct iovec iov[], unsigned int iov_size,
-		      unsigned int *out_num, unsigned int *in_num,
-		      struct vhost_log *log, unsigned int *log_num)
+static unsigned int vhost_get_vq_head(struct vhost_virtqueue *vq, int *err)
 {
-	struct vring_desc desc;
-	unsigned int i, head, found = 0;
-	u16 last_avail_idx;
-	__virtio16 avail_idx;
-	__virtio16 ring_head;
-	int ret, access;
-
-	/* Check it isn't doing very strange things with descriptor numbers. */
-	last_avail_idx = vq->last_avail_idx;
+	u16 last_avail_idx = vq->last_avail_idx;
+	__virtio16 avail_idx, ring_head;
 
 	if (vq->avail_idx == vq->last_avail_idx) {
 		if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
 			vq_err(vq, "Failed to access avail idx at %p\n",
 				&vq->avail->idx);
-			return -EFAULT;
+			goto err;
 		}
 		vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
 
 		if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
 			vq_err(vq, "Guest moved used index from %u to %u",
 				last_avail_idx, vq->avail_idx);
-			return -EFAULT;
+			goto err;
 		}
 
 		/* If there's nothing new since last we looked, return
@@ -2040,13 +2022,35 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
 		vq_err(vq, "Failed to read head: idx %d address %p\n",
 		       last_avail_idx,
 		       &vq->avail->ring[last_avail_idx % vq->num]);
-		return -EFAULT;
+		goto err;
 	}
 
-	head = vhost16_to_cpu(vq, ring_head);
+	return vhost16_to_cpu(vq, ring_head);
+err:
+	*err = -EFAULT;
+	return 0;
+}
+
+/* This looks in the virtqueue and for the first available buffer, and converts
+ * it to an iovec for convenient access.  Since descriptors consist of some
+ * number of output then some number of input descriptors, it's actually two
+ * iovecs, but we pack them into one and note how many of each there were.
+ *
+ * This function returns the descriptor number found, or vq->num (which is
+ * never a valid descriptor number) if none was found.  A negative code is
+ * returned on error. */
+int __vhost_get_vq_desc(struct vhost_virtqueue *vq,
+			struct iovec iov[], unsigned int iov_size,
+			unsigned int *out_num, unsigned int *in_num,
+			struct vhost_log *log, unsigned int *log_num,
+			__virtio16 head)
+{
+	struct vring_desc desc;
+	unsigned int i, found = 0;
+	int ret = 0, access;
 
 	/* If their number is silly, that's an error. */
-	if (unlikely(head >= vq->num)) {
+	if (unlikely(head > vq->num)) {
 		vq_err(vq, "Guest says index %u > %u is available",
 		       head, vq->num);
 		return -EINVAL;
@@ -2133,6 +2137,25 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
 	BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
 	return head;
 }
+EXPORT_SYMBOL_GPL(__vhost_get_vq_desc);
+
+int vhost_get_vq_desc(struct vhost_virtqueue *vq,
+		      struct iovec iov[], unsigned int iov_size,
+		      unsigned int *out_num, unsigned int *in_num,
+		      struct vhost_log *log, unsigned int *log_num)
+{
+	int ret = 0;
+	unsigned int head = vhost_get_vq_head(vq, &ret);
+
+	if (ret)
+		return ret;
+
+	if (head == vq->num)
+		return head;
+
+	return __vhost_get_vq_desc(vq, iov, iov_size, out_num, in_num,
+				   log, log_num, head);
+}
 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
 
 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index d59a9cc..39ff897 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -191,6 +191,11 @@ int vhost_get_vq_desc(struct vhost_virtqueue *,
 		      struct iovec iov[], unsigned int iov_count,
 		      unsigned int *out_num, unsigned int *in_num,
 		      struct vhost_log *log, unsigned int *log_num);
+int __vhost_get_vq_desc(struct vhost_virtqueue *vq,
+			struct iovec iov[], unsigned int iov_count,
+			unsigned int *out_num, unsigned int *in_num,
+			struct vhost_log *log, unsigned int *log_num,
+			__virtio16 ring_head);
 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 
 int vhost_vq_init_access(struct vhost_virtqueue *);
-- 
2.7.4

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#1737278 — Re: [PATCH net-next RFC 1/5] vhost: split out ring head fetching logic

On Fri, Sep 22, 2017 at 04:02:31PM +0800, Jason Wang wrote:
> +/* This looks in the virtqueue and for the first available buffer, and converts
> + * it to an iovec for convenient access.  Since descriptors consist of some
> + * number of output then some number of input descriptors, it's actually two
> + * iovecs, but we pack them into one and note how many of each there were.
> + *
> + * This function returns the descriptor number found, or vq->num (which is
> + * never a valid descriptor number) if none was found.  A negative code is
> + * returned on error. */
> +int __vhost_get_vq_desc(struct vhost_virtqueue *vq,
> +			struct iovec iov[], unsigned int iov_size,
> +			unsigned int *out_num, unsigned int *in_num,
> +			struct vhost_log *log, unsigned int *log_num,
> +			__virtio16 head)
[...]
> +int vhost_get_vq_desc(struct vhost_virtqueue *vq,
> +		      struct iovec iov[], unsigned int iov_size,
> +		      unsigned int *out_num, unsigned int *in_num,
> +		      struct vhost_log *log, unsigned int *log_num)

Please document vhost_get_vq_desc().

Please also explain the difference between __vhost_get_vq_desc() and
vhost_get_vq_desc() in the documentation.

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#1738710 — Re: [PATCH net-next RFC 1/5] vhost: split out ring head fetching logic

On 2017年09月22日 16:31, Stefan Hajnoczi wrote:
> On Fri, Sep 22, 2017 at 04:02:31PM +0800, Jason Wang wrote:
>> +/* This looks in the virtqueue and for the first available buffer, and converts
>> + * it to an iovec for convenient access.  Since descriptors consist of some
>> + * number of output then some number of input descriptors, it's actually two
>> + * iovecs, but we pack them into one and note how many of each there were.
>> + *
>> + * This function returns the descriptor number found, or vq->num (which is
>> + * never a valid descriptor number) if none was found.  A negative code is
>> + * returned on error. */
>> +int __vhost_get_vq_desc(struct vhost_virtqueue *vq,
>> +			struct iovec iov[], unsigned int iov_size,
>> +			unsigned int *out_num, unsigned int *in_num,
>> +			struct vhost_log *log, unsigned int *log_num,
>> +			__virtio16 head)
> [...]
>> +int vhost_get_vq_desc(struct vhost_virtqueue *vq,
>> +		      struct iovec iov[], unsigned int iov_size,
>> +		      unsigned int *out_num, unsigned int *in_num,
>> +		      struct vhost_log *log, unsigned int *log_num)
> Please document vhost_get_vq_desc().
>
> Please also explain the difference between __vhost_get_vq_desc() and
> vhost_get_vq_desc() in the documentation.

Right, will document this in next version.

Thanks

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#1739905

On Fri, Sep 22, 2017 at 04:02:30PM +0800, Jason Wang wrote:
> Hi:
> 
> This series tries to implement basic tx batched processing. This is
> done by prefetching descriptor indices and update used ring in a
> batch. This intends to speed up used ring updating and improve the
> cache utilization.

Interesting, thanks for the patches. So IIUC most of the gain is really
overcoming some of the shortcomings of virtio 1.0 wrt cache utilization?

Which is fair enough (1.0 is already deployed) but I would like to avoid
making 1.1 support harder, and this patchset does this unfortunately,
see comments on individual patches. I'm sure it can be addressed though.

> Test shows about ~22% improvement in tx pss.

Is this with or without tx napi in guest?

> Please review.
> 
> Jason Wang (5):
>   vhost: split out ring head fetching logic
>   vhost: introduce helper to prefetch desc index
>   vhost: introduce vhost_add_used_idx()
>   vhost_net: rename VHOST_RX_BATCH to VHOST_NET_BATCH
>   vhost_net: basic tx virtqueue batched processing
> 
>  drivers/vhost/net.c   | 221 ++++++++++++++++++++++++++++----------------------
>  drivers/vhost/vhost.c | 165 +++++++++++++++++++++++++++++++------
>  drivers/vhost/vhost.h |   9 ++
>  3 files changed, 270 insertions(+), 125 deletions(-)
> 
> -- 
> 2.7.4

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