diff mbox

[2/3] vhost-net: Unify the code of mergeable and big buffer handling

Message ID 20110117081108.18900.60053.stgit@dhcp-91-7.nay.redhat.com.englab.nay.redhat.com
State Awaiting Upstream, archived
Delegated to: David Miller
Headers show

Commit Message

Jason Wang Jan. 17, 2011, 8:11 a.m. UTC 
Codes duplication were found between the handling of mergeable and big
buffers, so this patch tries to unify them. This could be easily done
by adding a quota to the get_rx_bufs() which is used to limit the
number of buffers it returns (for mergeable buffer, the quota is
simply UIO_MAXIOV, for big buffers, the quota is just 1), and then the
previous handle_rx_mergeable() could be resued also for big buffers.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vhost/net.c |  128 +++------------------------------------------------
 1 files changed, 7 insertions(+), 121 deletions(-)


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Comments

Michael S. Tsirkin Jan. 17, 2011, 8:36 a.m. UTC | #1 
On Mon, Jan 17, 2011 at 04:11:08PM +0800, Jason Wang wrote:
> Codes duplication were found between the handling of mergeable and big
> buffers, so this patch tries to unify them. This could be easily done
> by adding a quota to the get_rx_bufs() which is used to limit the
> number of buffers it returns (for mergeable buffer, the quota is
> simply UIO_MAXIOV, for big buffers, the quota is just 1), and then the
> previous handle_rx_mergeable() could be resued also for big buffers.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>

We actually started this way. However the code turned out
to have measureable overhead when handle_rx_mergeable
is called with quota 1.
So before applying this I'd like to see some data
to show this is not the case anymore.

> ---
>  drivers/vhost/net.c |  128 +++------------------------------------------------
>  1 files changed, 7 insertions(+), 121 deletions(-)
> 
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 95e49de..c32a2e4 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -227,6 +227,7 @@ static int peek_head_len(struct sock *sk)
>   * @iovcount	- returned count of io vectors we fill
>   * @log		- vhost log
>   * @log_num	- log offset
> + * @quota       - headcount quota, 1 for big buffer
>   *	returns number of buffer heads allocated, negative on error
>   */
>  static int get_rx_bufs(struct vhost_virtqueue *vq,
> @@ -234,7 +235,8 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
>  		       int datalen,
>  		       unsigned *iovcount,
>  		       struct vhost_log *log,
> -		       unsigned *log_num)
> +		       unsigned *log_num,
> +		       unsigned int quota)
>  {
>  	unsigned int out, in;
>  	int seg = 0;
> @@ -242,7 +244,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
>  	unsigned d;
>  	int r, nlogs = 0;
>  
> -	while (datalen > 0) {
> +	while (datalen > 0 && headcount < quota) {
>  		if (unlikely(seg >= UIO_MAXIOV)) {
>  			r = -ENOBUFS;
>  			goto err;
> @@ -282,116 +284,7 @@ err:
>  
>  /* Expects to be always run from workqueue - which acts as
>   * read-size critical section for our kind of RCU. */
> -static void handle_rx_big(struct vhost_net *net)
> -{
> -	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
> -	unsigned out, in, log, s;
> -	int head;
> -	struct vhost_log *vq_log;
> -	struct msghdr msg = {
> -		.msg_name = NULL,
> -		.msg_namelen = 0,
> -		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
> -		.msg_controllen = 0,
> -		.msg_iov = vq->iov,
> -		.msg_flags = MSG_DONTWAIT,
> -	};
> -
> -	struct virtio_net_hdr hdr = {
> -		.flags = 0,
> -		.gso_type = VIRTIO_NET_HDR_GSO_NONE
> -	};
> -
> -	size_t len, total_len = 0;
> -	int err;
> -	size_t hdr_size;
> -	struct socket *sock = rcu_dereference(vq->private_data);
> -	if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
> -		return;
> -
> -	mutex_lock(&vq->mutex);
> -	vhost_disable_notify(vq);
> -	hdr_size = vq->vhost_hlen;
> -
> -	vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
> -		vq->log : NULL;
> -
> -	for (;;) {
> -		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
> -					 ARRAY_SIZE(vq->iov),
> -					 &out, &in,
> -					 vq_log, &log);
> -		/* On error, stop handling until the next kick. */
> -		if (unlikely(head < 0))
> -			break;
> -		/* OK, now we need to know about added descriptors. */
> -		if (head == vq->num) {
> -			if (unlikely(vhost_enable_notify(vq))) {
> -				/* They have slipped one in as we were
> -				 * doing that: check again. */
> -				vhost_disable_notify(vq);
> -				continue;
> -			}
> -			/* Nothing new?  Wait for eventfd to tell us
> -			 * they refilled. */
> -			break;
> -		}
> -		/* We don't need to be notified again. */
> -		if (out) {
> -			vq_err(vq, "Unexpected descriptor format for RX: "
> -			       "out %d, int %d\n",
> -			       out, in);
> -			break;
> -		}
> -		/* Skip header. TODO: support TSO/mergeable rx buffers. */
> -		s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
> -		msg.msg_iovlen = in;
> -		len = iov_length(vq->iov, in);
> -		/* Sanity check */
> -		if (!len) {
> -			vq_err(vq, "Unexpected header len for RX: "
> -			       "%zd expected %zd\n",
> -			       iov_length(vq->hdr, s), hdr_size);
> -			break;
> -		}
> -		err = sock->ops->recvmsg(NULL, sock, &msg,
> -					 len, MSG_DONTWAIT | MSG_TRUNC);
> -		/* TODO: Check specific error and bomb out unless EAGAIN? */
> -		if (err < 0) {
> -			vhost_discard_vq_desc(vq, 1);
> -			break;
> -		}
> -		/* TODO: Should check and handle checksum. */
> -		if (err > len) {
> -			pr_debug("Discarded truncated rx packet: "
> -				 " len %d > %zd\n", err, len);
> -			vhost_discard_vq_desc(vq, 1);
> -			continue;
> -		}
> -		len = err;
> -		err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size);
> -		if (err) {
> -			vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n",
> -			       vq->iov->iov_base, err);
> -			break;
> -		}
> -		len += hdr_size;
> -		vhost_add_used_and_signal(&net->dev, vq, head, len);
> -		if (unlikely(vq_log))
> -			vhost_log_write(vq, vq_log, log, len);
> -		total_len += len;
> -		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
> -			vhost_poll_queue(&vq->poll);
> -			break;
> -		}
> -	}
> -
> -	mutex_unlock(&vq->mutex);
> -}
> -
> -/* Expects to be always run from workqueue - which acts as
> - * read-size critical section for our kind of RCU. */
> -static void handle_rx_mergeable(struct vhost_net *net)
> +static void handle_rx(struct vhost_net *net)
>  {
>  	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
>  	unsigned uninitialized_var(in), log;
> @@ -431,7 +324,8 @@ static void handle_rx_mergeable(struct vhost_net *net)
>  		sock_len += sock_hlen;
>  		vhost_len = sock_len + vhost_hlen;
>  		headcount = get_rx_bufs(vq, vq->heads, vhost_len,
> -					&in, vq_log, &log);
> +					&in, vq_log, &log,
> +					likely(mergeable) ? UIO_MAXIOV : 1);
>  		/* On error, stop handling until the next kick. */
>  		if (unlikely(headcount < 0))
>  			break;
> @@ -497,14 +391,6 @@ static void handle_rx_mergeable(struct vhost_net *net)
>  	mutex_unlock(&vq->mutex);
>  }
>  
> -static void handle_rx(struct vhost_net *net)
> -{
> -	if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF))
> -		handle_rx_mergeable(net);
> -	else
> -		handle_rx_big(net);
> -}
> -
>  static void handle_tx_kick(struct vhost_work *work)
>  {
>  	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
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Jason Wang Jan. 18, 2011, 3:05 a.m. UTC | #2 
Michael S. Tsirkin writes:
 > On Mon, Jan 17, 2011 at 04:11:08PM +0800, Jason Wang wrote:
 > > Codes duplication were found between the handling of mergeable and big
 > > buffers, so this patch tries to unify them. This could be easily done
 > > by adding a quota to the get_rx_bufs() which is used to limit the
 > > number of buffers it returns (for mergeable buffer, the quota is
 > > simply UIO_MAXIOV, for big buffers, the quota is just 1), and then the
 > > previous handle_rx_mergeable() could be resued also for big buffers.
 > > 
 > > Signed-off-by: Jason Wang <jasowang@redhat.com>
 > 
 > We actually started this way. However the code turned out
 > to have measureable overhead when handle_rx_mergeable
 > is called with quota 1.
 > So before applying this I'd like to see some data
 > to show this is not the case anymore.
 > 

I've run a round of test (Host->Guest) for these three patches on my desktop:

Without these patches

mergeable buffers:
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.42 (10.66.91.42) port 0 AF_INET
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB

 87380  16384     64    60.00       575.87   69.20    26.36    39.375  7.499  
 87380  16384    256    60.01      1123.57   73.16    34.73    21.335  5.064  
 87380  16384    512    60.00      1351.12   75.26    35.80    18.251  4.341  
 87380  16384   1024    60.00      1955.31   74.73    37.67    12.523  3.156  
 87380  16384   2048    60.01      3411.92   74.82    39.49    7.186   1.896  

bug buffers:
Netperf test results
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.109 (10.66.91.109) port 0 AF_INET
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB

 87380  16384     64    60.00       567.10   72.06    26.13    41.638  7.550  
 87380  16384    256    60.00      1143.69   74.66    32.58    21.392  4.667  
 87380  16384    512    60.00      1460.92   73.94    33.40    16.585  3.746  
 87380  16384   1024    60.00      3454.85   77.49    33.89    7.349   1.607  
 87380  16384   2048    60.00      3781.11   76.51    38.38    6.631   1.663  

With these patches:

mergeable buffers:
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.236 (10.66.91.236) port 0 AF_INET
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB

 87380  16384     64    60.00       657.53   71.27    26.42    35.517  6.583  
 87380  16384    256    60.00      1217.73   74.34    34.67    20.004  4.665  
 87380  16384    512    60.00      1575.25   75.27    37.12    15.658  3.861  
 87380  16384   1024    60.00      2416.07   74.77    37.20    10.140  2.522  
 87380  16384   2048    60.00      3702.29   77.31    36.29    6.842   1.606  

big buffers:
Netperf test results
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.202 (10.66.91.202) port 0 AF_INET
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB

 87380  16384     64    60.00       647.67   71.86    27.26    36.356  6.895  
 87380  16384    256    60.00      1265.82   76.19    36.54    19.724  4.729  
 87380  16384    512    60.00      1796.64   76.06    39.48    13.872  3.601  
 87380  16384   1024    60.00      4008.37   77.05    36.47    6.299   1.491  
 87380  16384   2048    60.00      4468.56   75.18    41.79    5.513   1.532 

Looks like the unification does not hurt the performance, and with those patches
we can get some improvement. BTW, the regression of mergeable buffer still
exist.

 > > ---
 > >  drivers/vhost/net.c |  128 +++------------------------------------------------
 > >  1 files changed, 7 insertions(+), 121 deletions(-)
 > > 
 > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
 > > index 95e49de..c32a2e4 100644
 > > --- a/drivers/vhost/net.c
 > > +++ b/drivers/vhost/net.c
 > > @@ -227,6 +227,7 @@ static int peek_head_len(struct sock *sk)
 > >   * @iovcount	- returned count of io vectors we fill
 > >   * @log		- vhost log
 > >   * @log_num	- log offset
 > > + * @quota       - headcount quota, 1 for big buffer
 > >   *	returns number of buffer heads allocated, negative on error
 > >   */
 > >  static int get_rx_bufs(struct vhost_virtqueue *vq,
 > > @@ -234,7 +235,8 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
 > >  		       int datalen,
 > >  		       unsigned *iovcount,
 > >  		       struct vhost_log *log,
 > > -		       unsigned *log_num)
 > > +		       unsigned *log_num,
 > > +		       unsigned int quota)
 > >  {
 > >  	unsigned int out, in;
 > >  	int seg = 0;
 > > @@ -242,7 +244,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
 > >  	unsigned d;
 > >  	int r, nlogs = 0;
 > >  
 > > -	while (datalen > 0) {
 > > +	while (datalen > 0 && headcount < quota) {
 > >  		if (unlikely(seg >= UIO_MAXIOV)) {
 > >  			r = -ENOBUFS;
 > >  			goto err;
 > > @@ -282,116 +284,7 @@ err:
 > >  
 > >  /* Expects to be always run from workqueue - which acts as
 > >   * read-size critical section for our kind of RCU. */
 > > -static void handle_rx_big(struct vhost_net *net)
 > > -{
 > > -	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 > > -	unsigned out, in, log, s;
 > > -	int head;
 > > -	struct vhost_log *vq_log;
 > > -	struct msghdr msg = {
 > > -		.msg_name = NULL,
 > > -		.msg_namelen = 0,
 > > -		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
 > > -		.msg_controllen = 0,
 > > -		.msg_iov = vq->iov,
 > > -		.msg_flags = MSG_DONTWAIT,
 > > -	};
 > > -
 > > -	struct virtio_net_hdr hdr = {
 > > -		.flags = 0,
 > > -		.gso_type = VIRTIO_NET_HDR_GSO_NONE
 > > -	};
 > > -
 > > -	size_t len, total_len = 0;
 > > -	int err;
 > > -	size_t hdr_size;
 > > -	struct socket *sock = rcu_dereference(vq->private_data);
 > > -	if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
 > > -		return;
 > > -
 > > -	mutex_lock(&vq->mutex);
 > > -	vhost_disable_notify(vq);
 > > -	hdr_size = vq->vhost_hlen;
 > > -
 > > -	vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 > > -		vq->log : NULL;
 > > -
 > > -	for (;;) {
 > > -		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
 > > -					 ARRAY_SIZE(vq->iov),
 > > -					 &out, &in,
 > > -					 vq_log, &log);
 > > -		/* On error, stop handling until the next kick. */
 > > -		if (unlikely(head < 0))
 > > -			break;
 > > -		/* OK, now we need to know about added descriptors. */
 > > -		if (head == vq->num) {
 > > -			if (unlikely(vhost_enable_notify(vq))) {
 > > -				/* They have slipped one in as we were
 > > -				 * doing that: check again. */
 > > -				vhost_disable_notify(vq);
 > > -				continue;
 > > -			}
 > > -			/* Nothing new?  Wait for eventfd to tell us
 > > -			 * they refilled. */
 > > -			break;
 > > -		}
 > > -		/* We don't need to be notified again. */
 > > -		if (out) {
 > > -			vq_err(vq, "Unexpected descriptor format for RX: "
 > > -			       "out %d, int %d\n",
 > > -			       out, in);
 > > -			break;
 > > -		}
 > > -		/* Skip header. TODO: support TSO/mergeable rx buffers. */
 > > -		s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
 > > -		msg.msg_iovlen = in;
 > > -		len = iov_length(vq->iov, in);
 > > -		/* Sanity check */
 > > -		if (!len) {
 > > -			vq_err(vq, "Unexpected header len for RX: "
 > > -			       "%zd expected %zd\n",
 > > -			       iov_length(vq->hdr, s), hdr_size);
 > > -			break;
 > > -		}
 > > -		err = sock->ops->recvmsg(NULL, sock, &msg,
 > > -					 len, MSG_DONTWAIT | MSG_TRUNC);
 > > -		/* TODO: Check specific error and bomb out unless EAGAIN? */
 > > -		if (err < 0) {
 > > -			vhost_discard_vq_desc(vq, 1);
 > > -			break;
 > > -		}
 > > -		/* TODO: Should check and handle checksum. */
 > > -		if (err > len) {
 > > -			pr_debug("Discarded truncated rx packet: "
 > > -				 " len %d > %zd\n", err, len);
 > > -			vhost_discard_vq_desc(vq, 1);
 > > -			continue;
 > > -		}
 > > -		len = err;
 > > -		err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size);
 > > -		if (err) {
 > > -			vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n",
 > > -			       vq->iov->iov_base, err);
 > > -			break;
 > > -		}
 > > -		len += hdr_size;
 > > -		vhost_add_used_and_signal(&net->dev, vq, head, len);
 > > -		if (unlikely(vq_log))
 > > -			vhost_log_write(vq, vq_log, log, len);
 > > -		total_len += len;
 > > -		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 > > -			vhost_poll_queue(&vq->poll);
 > > -			break;
 > > -		}
 > > -	}
 > > -
 > > -	mutex_unlock(&vq->mutex);
 > > -}
 > > -
 > > -/* Expects to be always run from workqueue - which acts as
 > > - * read-size critical section for our kind of RCU. */
 > > -static void handle_rx_mergeable(struct vhost_net *net)
 > > +static void handle_rx(struct vhost_net *net)
 > >  {
 > >  	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 > >  	unsigned uninitialized_var(in), log;
 > > @@ -431,7 +324,8 @@ static void handle_rx_mergeable(struct vhost_net *net)
 > >  		sock_len += sock_hlen;
 > >  		vhost_len = sock_len + vhost_hlen;
 > >  		headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 > > -					&in, vq_log, &log);
 > > +					&in, vq_log, &log,
 > > +					likely(mergeable) ? UIO_MAXIOV : 1);
 > >  		/* On error, stop handling until the next kick. */
 > >  		if (unlikely(headcount < 0))
 > >  			break;
 > > @@ -497,14 +391,6 @@ static void handle_rx_mergeable(struct vhost_net *net)
 > >  	mutex_unlock(&vq->mutex);
 > >  }
 > >  
 > > -static void handle_rx(struct vhost_net *net)
 > > -{
 > > -	if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF))
 > > -		handle_rx_mergeable(net);
 > > -	else
 > > -		handle_rx_big(net);
 > > -}
 > > -
 > >  static void handle_tx_kick(struct vhost_work *work)
 > >  {
 > >  	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
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Michael S. Tsirkin Jan. 18, 2011, 4:37 a.m. UTC | #3 
On Tue, Jan 18, 2011 at 11:05:33AM +0800, Jason Wang wrote:
> Michael S. Tsirkin writes:
>  > On Mon, Jan 17, 2011 at 04:11:08PM +0800, Jason Wang wrote:
>  > > Codes duplication were found between the handling of mergeable and big
>  > > buffers, so this patch tries to unify them. This could be easily done
>  > > by adding a quota to the get_rx_bufs() which is used to limit the
>  > > number of buffers it returns (for mergeable buffer, the quota is
>  > > simply UIO_MAXIOV, for big buffers, the quota is just 1), and then the
>  > > previous handle_rx_mergeable() could be resued also for big buffers.
>  > > 
>  > > Signed-off-by: Jason Wang <jasowang@redhat.com>
>  > 
>  > We actually started this way. However the code turned out
>  > to have measureable overhead when handle_rx_mergeable
>  > is called with quota 1.
>  > So before applying this I'd like to see some data
>  > to show this is not the case anymore.
>  > 
> 
> I've run a round of test (Host->Guest) for these three patches on my desktop:

Yes but what if you only apply patch 3?

> Without these patches
> 
> mergeable buffers:
> TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.42 (10.66.91.42) port 0 AF_INET
> Recv   Send    Send                          Utilization       Service Demand
> Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
> Size   Size    Size     Time     Throughput  local    remote   local   remote
> bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
> 
>  87380  16384     64    60.00       575.87   69.20    26.36    39.375  7.499  
>  87380  16384    256    60.01      1123.57   73.16    34.73    21.335  5.064  
>  87380  16384    512    60.00      1351.12   75.26    35.80    18.251  4.341  
>  87380  16384   1024    60.00      1955.31   74.73    37.67    12.523  3.156  
>  87380  16384   2048    60.01      3411.92   74.82    39.49    7.186   1.896  
> 
> bug buffers:
> Netperf test results
> TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.109 (10.66.91.109) port 0 AF_INET
> Recv   Send    Send                          Utilization       Service Demand
> Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
> Size   Size    Size     Time     Throughput  local    remote   local   remote
> bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
> 
>  87380  16384     64    60.00       567.10   72.06    26.13    41.638  7.550  
>  87380  16384    256    60.00      1143.69   74.66    32.58    21.392  4.667  
>  87380  16384    512    60.00      1460.92   73.94    33.40    16.585  3.746  
>  87380  16384   1024    60.00      3454.85   77.49    33.89    7.349   1.607  
>  87380  16384   2048    60.00      3781.11   76.51    38.38    6.631   1.663  
> 
> With these patches:
> 
> mergeable buffers:
> TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.236 (10.66.91.236) port 0 AF_INET
> Recv   Send    Send                          Utilization       Service Demand
> Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
> Size   Size    Size     Time     Throughput  local    remote   local   remote
> bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
> 
>  87380  16384     64    60.00       657.53   71.27    26.42    35.517  6.583  
>  87380  16384    256    60.00      1217.73   74.34    34.67    20.004  4.665  
>  87380  16384    512    60.00      1575.25   75.27    37.12    15.658  3.861  
>  87380  16384   1024    60.00      2416.07   74.77    37.20    10.140  2.522  
>  87380  16384   2048    60.00      3702.29   77.31    36.29    6.842   1.606  
> 
> big buffers:
> Netperf test results
> TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.202 (10.66.91.202) port 0 AF_INET
> Recv   Send    Send                          Utilization       Service Demand
> Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
> Size   Size    Size     Time     Throughput  local    remote   local   remote
> bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
> 
>  87380  16384     64    60.00       647.67   71.86    27.26    36.356  6.895  
>  87380  16384    256    60.00      1265.82   76.19    36.54    19.724  4.729  
>  87380  16384    512    60.00      1796.64   76.06    39.48    13.872  3.601  
>  87380  16384   1024    60.00      4008.37   77.05    36.47    6.299   1.491  
>  87380  16384   2048    60.00      4468.56   75.18    41.79    5.513   1.532 
> 
> Looks like the unification does not hurt the performance, and with those patches
> we can get some improvement. BTW, the regression of mergeable buffer still
> exist.
> 
>  > > ---
>  > >  drivers/vhost/net.c |  128 +++------------------------------------------------
>  > >  1 files changed, 7 insertions(+), 121 deletions(-)
>  > > 
>  > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
>  > > index 95e49de..c32a2e4 100644
>  > > --- a/drivers/vhost/net.c
>  > > +++ b/drivers/vhost/net.c
>  > > @@ -227,6 +227,7 @@ static int peek_head_len(struct sock *sk)
>  > >   * @iovcount	- returned count of io vectors we fill
>  > >   * @log		- vhost log
>  > >   * @log_num	- log offset
>  > > + * @quota       - headcount quota, 1 for big buffer
>  > >   *	returns number of buffer heads allocated, negative on error
>  > >   */
>  > >  static int get_rx_bufs(struct vhost_virtqueue *vq,
>  > > @@ -234,7 +235,8 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
>  > >  		       int datalen,
>  > >  		       unsigned *iovcount,
>  > >  		       struct vhost_log *log,
>  > > -		       unsigned *log_num)
>  > > +		       unsigned *log_num,
>  > > +		       unsigned int quota)
>  > >  {
>  > >  	unsigned int out, in;
>  > >  	int seg = 0;
>  > > @@ -242,7 +244,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
>  > >  	unsigned d;
>  > >  	int r, nlogs = 0;
>  > >  
>  > > -	while (datalen > 0) {
>  > > +	while (datalen > 0 && headcount < quota) {
>  > >  		if (unlikely(seg >= UIO_MAXIOV)) {
>  > >  			r = -ENOBUFS;
>  > >  			goto err;
>  > > @@ -282,116 +284,7 @@ err:
>  > >  
>  > >  /* Expects to be always run from workqueue - which acts as
>  > >   * read-size critical section for our kind of RCU. */
>  > > -static void handle_rx_big(struct vhost_net *net)
>  > > -{
>  > > -	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
>  > > -	unsigned out, in, log, s;
>  > > -	int head;
>  > > -	struct vhost_log *vq_log;
>  > > -	struct msghdr msg = {
>  > > -		.msg_name = NULL,
>  > > -		.msg_namelen = 0,
>  > > -		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
>  > > -		.msg_controllen = 0,
>  > > -		.msg_iov = vq->iov,
>  > > -		.msg_flags = MSG_DONTWAIT,
>  > > -	};
>  > > -
>  > > -	struct virtio_net_hdr hdr = {
>  > > -		.flags = 0,
>  > > -		.gso_type = VIRTIO_NET_HDR_GSO_NONE
>  > > -	};
>  > > -
>  > > -	size_t len, total_len = 0;
>  > > -	int err;
>  > > -	size_t hdr_size;
>  > > -	struct socket *sock = rcu_dereference(vq->private_data);
>  > > -	if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
>  > > -		return;
>  > > -
>  > > -	mutex_lock(&vq->mutex);
>  > > -	vhost_disable_notify(vq);
>  > > -	hdr_size = vq->vhost_hlen;
>  > > -
>  > > -	vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
>  > > -		vq->log : NULL;
>  > > -
>  > > -	for (;;) {
>  > > -		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
>  > > -					 ARRAY_SIZE(vq->iov),
>  > > -					 &out, &in,
>  > > -					 vq_log, &log);
>  > > -		/* On error, stop handling until the next kick. */
>  > > -		if (unlikely(head < 0))
>  > > -			break;
>  > > -		/* OK, now we need to know about added descriptors. */
>  > > -		if (head == vq->num) {
>  > > -			if (unlikely(vhost_enable_notify(vq))) {
>  > > -				/* They have slipped one in as we were
>  > > -				 * doing that: check again. */
>  > > -				vhost_disable_notify(vq);
>  > > -				continue;
>  > > -			}
>  > > -			/* Nothing new?  Wait for eventfd to tell us
>  > > -			 * they refilled. */
>  > > -			break;
>  > > -		}
>  > > -		/* We don't need to be notified again. */
>  > > -		if (out) {
>  > > -			vq_err(vq, "Unexpected descriptor format for RX: "
>  > > -			       "out %d, int %d\n",
>  > > -			       out, in);
>  > > -			break;
>  > > -		}
>  > > -		/* Skip header. TODO: support TSO/mergeable rx buffers. */
>  > > -		s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
>  > > -		msg.msg_iovlen = in;
>  > > -		len = iov_length(vq->iov, in);
>  > > -		/* Sanity check */
>  > > -		if (!len) {
>  > > -			vq_err(vq, "Unexpected header len for RX: "
>  > > -			       "%zd expected %zd\n",
>  > > -			       iov_length(vq->hdr, s), hdr_size);
>  > > -			break;
>  > > -		}
>  > > -		err = sock->ops->recvmsg(NULL, sock, &msg,
>  > > -					 len, MSG_DONTWAIT | MSG_TRUNC);
>  > > -		/* TODO: Check specific error and bomb out unless EAGAIN? */
>  > > -		if (err < 0) {
>  > > -			vhost_discard_vq_desc(vq, 1);
>  > > -			break;
>  > > -		}
>  > > -		/* TODO: Should check and handle checksum. */
>  > > -		if (err > len) {
>  > > -			pr_debug("Discarded truncated rx packet: "
>  > > -				 " len %d > %zd\n", err, len);
>  > > -			vhost_discard_vq_desc(vq, 1);
>  > > -			continue;
>  > > -		}
>  > > -		len = err;
>  > > -		err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size);
>  > > -		if (err) {
>  > > -			vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n",
>  > > -			       vq->iov->iov_base, err);
>  > > -			break;
>  > > -		}
>  > > -		len += hdr_size;
>  > > -		vhost_add_used_and_signal(&net->dev, vq, head, len);
>  > > -		if (unlikely(vq_log))
>  > > -			vhost_log_write(vq, vq_log, log, len);
>  > > -		total_len += len;
>  > > -		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
>  > > -			vhost_poll_queue(&vq->poll);
>  > > -			break;
>  > > -		}
>  > > -	}
>  > > -
>  > > -	mutex_unlock(&vq->mutex);
>  > > -}
>  > > -
>  > > -/* Expects to be always run from workqueue - which acts as
>  > > - * read-size critical section for our kind of RCU. */
>  > > -static void handle_rx_mergeable(struct vhost_net *net)
>  > > +static void handle_rx(struct vhost_net *net)
>  > >  {
>  > >  	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
>  > >  	unsigned uninitialized_var(in), log;
>  > > @@ -431,7 +324,8 @@ static void handle_rx_mergeable(struct vhost_net *net)
>  > >  		sock_len += sock_hlen;
>  > >  		vhost_len = sock_len + vhost_hlen;
>  > >  		headcount = get_rx_bufs(vq, vq->heads, vhost_len,
>  > > -					&in, vq_log, &log);
>  > > +					&in, vq_log, &log,
>  > > +					likely(mergeable) ? UIO_MAXIOV : 1);
>  > >  		/* On error, stop handling until the next kick. */
>  > >  		if (unlikely(headcount < 0))
>  > >  			break;
>  > > @@ -497,14 +391,6 @@ static void handle_rx_mergeable(struct vhost_net *net)
>  > >  	mutex_unlock(&vq->mutex);
>  > >  }
>  > >  
>  > > -static void handle_rx(struct vhost_net *net)
>  > > -{
>  > > -	if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF))
>  > > -		handle_rx_mergeable(net);
>  > > -	else
>  > > -		handle_rx_big(net);
>  > > -}
>  > > -
>  > >  static void handle_tx_kick(struct vhost_work *work)
>  > >  {
>  > >  	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
--
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Jason Wang Jan. 18, 2011, 7:41 a.m. UTC | #4 
Michael S. Tsirkin writes:
 > On Tue, Jan 18, 2011 at 11:05:33AM +0800, Jason Wang wrote:
 > > Michael S. Tsirkin writes:
 > >  > On Mon, Jan 17, 2011 at 04:11:08PM +0800, Jason Wang wrote:
 > >  > > Codes duplication were found between the handling of mergeable and big
 > >  > > buffers, so this patch tries to unify them. This could be easily done
 > >  > > by adding a quota to the get_rx_bufs() which is used to limit the
 > >  > > number of buffers it returns (for mergeable buffer, the quota is
 > >  > > simply UIO_MAXIOV, for big buffers, the quota is just 1), and then the
 > >  > > previous handle_rx_mergeable() could be resued also for big buffers.
 > >  > > 
 > >  > > Signed-off-by: Jason Wang <jasowang@redhat.com>
 > >  > 
 > >  > We actually started this way. However the code turned out
 > >  > to have measureable overhead when handle_rx_mergeable
 > >  > is called with quota 1.
 > >  > So before applying this I'd like to see some data
 > >  > to show this is not the case anymore.
 > >  > 
 > > 
 > > I've run a round of test (Host->Guest) for these three patches on my desktop:
 > 
 > Yes but what if you only apply patch 3?
 > 

Result here, slightly better than without it but worse than applying all the three
patches except for big buffer size at 2048 but the differnece could be neglected.

mergeable buffers:
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.161 (10.66.91.161) port 0 AF_INET
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB

 87380  16384     64    60.00       584.91   69.41    26.10    38.882  7.310  
 87380  16384    256    60.00      1194.05   72.81    34.82    19.980  4.778  
 87380  16384    512    60.00      1503.93   74.23    36.86    16.174  4.016  
 87380  16384   1024    60.00      2004.57   73.53    37.59    12.019  3.073  
 87380  16384   2048    60.00      3445.96   73.76    38.88    7.014   1.849  

big buffers:
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.129 (10.66.91.129) port 0 AF_INET
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB

 87380  16384     64    60.00       646.95   72.25    27.05    36.595  6.850  
 87380  16384    256    60.00      1258.61   74.88    33.01    19.495  4.297  
 87380  16384    512    60.00      1655.95   74.14    33.96    14.671  3.360  
 87380  16384   1024    60.00      3220.32   74.24    33.31    7.555   1.695  
 87380  16384   2048    60.00      4516.40   73.88    42.10    5.360   1.527  

 > > Without these patches
 > > 
 > > mergeable buffers:
 > > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.42 (10.66.91.42) port 0 AF_INET
 > > Recv   Send    Send                          Utilization       Service Demand
 > > Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
 > > Size   Size    Size     Time     Throughput  local    remote   local   remote
 > > bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
 > > 
 > >  87380  16384     64    60.00       575.87   69.20    26.36    39.375  7.499  
 > >  87380  16384    256    60.01      1123.57   73.16    34.73    21.335  5.064  
 > >  87380  16384    512    60.00      1351.12   75.26    35.80    18.251  4.341  
 > >  87380  16384   1024    60.00      1955.31   74.73    37.67    12.523  3.156  
 > >  87380  16384   2048    60.01      3411.92   74.82    39.49    7.186   1.896  
 > > 
 > > bug buffers:
 > > Netperf test results
 > > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.109 (10.66.91.109) port 0 AF_INET
 > > Recv   Send    Send                          Utilization       Service Demand
 > > Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
 > > Size   Size    Size     Time     Throughput  local    remote   local   remote
 > > bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
 > > 
 > >  87380  16384     64    60.00       567.10   72.06    26.13    41.638  7.550  
 > >  87380  16384    256    60.00      1143.69   74.66    32.58    21.392  4.667  
 > >  87380  16384    512    60.00      1460.92   73.94    33.40    16.585  3.746  
 > >  87380  16384   1024    60.00      3454.85   77.49    33.89    7.349   1.607  
 > >  87380  16384   2048    60.00      3781.11   76.51    38.38    6.631   1.663  
 > > 
 > > With these patches:
 > > 
 > > mergeable buffers:
 > > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.236 (10.66.91.236) port 0 AF_INET
 > > Recv   Send    Send                          Utilization       Service Demand
 > > Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
 > > Size   Size    Size     Time     Throughput  local    remote   local   remote
 > > bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
 > > 
 > >  87380  16384     64    60.00       657.53   71.27    26.42    35.517  6.583  
 > >  87380  16384    256    60.00      1217.73   74.34    34.67    20.004  4.665  
 > >  87380  16384    512    60.00      1575.25   75.27    37.12    15.658  3.861  
 > >  87380  16384   1024    60.00      2416.07   74.77    37.20    10.140  2.522  
 > >  87380  16384   2048    60.00      3702.29   77.31    36.29    6.842   1.606  
 > > 
 > > big buffers:
 > > Netperf test results
 > > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.66.91.202 (10.66.91.202) port 0 AF_INET
 > > Recv   Send    Send                          Utilization       Service Demand
 > > Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
 > > Size   Size    Size     Time     Throughput  local    remote   local   remote
 > > bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
 > > 
 > >  87380  16384     64    60.00       647.67   71.86    27.26    36.356  6.895  
 > >  87380  16384    256    60.00      1265.82   76.19    36.54    19.724  4.729  
 > >  87380  16384    512    60.00      1796.64   76.06    39.48    13.872  3.601  
 > >  87380  16384   1024    60.00      4008.37   77.05    36.47    6.299   1.491  
 > >  87380  16384   2048    60.00      4468.56   75.18    41.79    5.513   1.532 
 > > 
 > > Looks like the unification does not hurt the performance, and with those patches
 > > we can get some improvement. BTW, the regression of mergeable buffer still
 > > exist.
 > > 
 > >  > > ---
 > >  > >  drivers/vhost/net.c |  128 +++------------------------------------------------
 > >  > >  1 files changed, 7 insertions(+), 121 deletions(-)
 > >  > > 
 > >  > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
 > >  > > index 95e49de..c32a2e4 100644
 > >  > > --- a/drivers/vhost/net.c
 > >  > > +++ b/drivers/vhost/net.c
 > >  > > @@ -227,6 +227,7 @@ static int peek_head_len(struct sock *sk)
 > >  > >   * @iovcount	- returned count of io vectors we fill
 > >  > >   * @log		- vhost log
 > >  > >   * @log_num	- log offset
 > >  > > + * @quota       - headcount quota, 1 for big buffer
 > >  > >   *	returns number of buffer heads allocated, negative on error
 > >  > >   */
 > >  > >  static int get_rx_bufs(struct vhost_virtqueue *vq,
 > >  > > @@ -234,7 +235,8 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
 > >  > >  		       int datalen,
 > >  > >  		       unsigned *iovcount,
 > >  > >  		       struct vhost_log *log,
 > >  > > -		       unsigned *log_num)
 > >  > > +		       unsigned *log_num,
 > >  > > +		       unsigned int quota)
 > >  > >  {
 > >  > >  	unsigned int out, in;
 > >  > >  	int seg = 0;
 > >  > > @@ -242,7 +244,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
 > >  > >  	unsigned d;
 > >  > >  	int r, nlogs = 0;
 > >  > >  
 > >  > > -	while (datalen > 0) {
 > >  > > +	while (datalen > 0 && headcount < quota) {
 > >  > >  		if (unlikely(seg >= UIO_MAXIOV)) {
 > >  > >  			r = -ENOBUFS;
 > >  > >  			goto err;
 > >  > > @@ -282,116 +284,7 @@ err:
 > >  > >  
 > >  > >  /* Expects to be always run from workqueue - which acts as
 > >  > >   * read-size critical section for our kind of RCU. */
 > >  > > -static void handle_rx_big(struct vhost_net *net)
 > >  > > -{
 > >  > > -	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 > >  > > -	unsigned out, in, log, s;
 > >  > > -	int head;
 > >  > > -	struct vhost_log *vq_log;
 > >  > > -	struct msghdr msg = {
 > >  > > -		.msg_name = NULL,
 > >  > > -		.msg_namelen = 0,
 > >  > > -		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
 > >  > > -		.msg_controllen = 0,
 > >  > > -		.msg_iov = vq->iov,
 > >  > > -		.msg_flags = MSG_DONTWAIT,
 > >  > > -	};
 > >  > > -
 > >  > > -	struct virtio_net_hdr hdr = {
 > >  > > -		.flags = 0,
 > >  > > -		.gso_type = VIRTIO_NET_HDR_GSO_NONE
 > >  > > -	};
 > >  > > -
 > >  > > -	size_t len, total_len = 0;
 > >  > > -	int err;
 > >  > > -	size_t hdr_size;
 > >  > > -	struct socket *sock = rcu_dereference(vq->private_data);
 > >  > > -	if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
 > >  > > -		return;
 > >  > > -
 > >  > > -	mutex_lock(&vq->mutex);
 > >  > > -	vhost_disable_notify(vq);
 > >  > > -	hdr_size = vq->vhost_hlen;
 > >  > > -
 > >  > > -	vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 > >  > > -		vq->log : NULL;
 > >  > > -
 > >  > > -	for (;;) {
 > >  > > -		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
 > >  > > -					 ARRAY_SIZE(vq->iov),
 > >  > > -					 &out, &in,
 > >  > > -					 vq_log, &log);
 > >  > > -		/* On error, stop handling until the next kick. */
 > >  > > -		if (unlikely(head < 0))
 > >  > > -			break;
 > >  > > -		/* OK, now we need to know about added descriptors. */
 > >  > > -		if (head == vq->num) {
 > >  > > -			if (unlikely(vhost_enable_notify(vq))) {
 > >  > > -				/* They have slipped one in as we were
 > >  > > -				 * doing that: check again. */
 > >  > > -				vhost_disable_notify(vq);
 > >  > > -				continue;
 > >  > > -			}
 > >  > > -			/* Nothing new?  Wait for eventfd to tell us
 > >  > > -			 * they refilled. */
 > >  > > -			break;
 > >  > > -		}
 > >  > > -		/* We don't need to be notified again. */
 > >  > > -		if (out) {
 > >  > > -			vq_err(vq, "Unexpected descriptor format for RX: "
 > >  > > -			       "out %d, int %d\n",
 > >  > > -			       out, in);
 > >  > > -			break;
 > >  > > -		}
 > >  > > -		/* Skip header. TODO: support TSO/mergeable rx buffers. */
 > >  > > -		s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
 > >  > > -		msg.msg_iovlen = in;
 > >  > > -		len = iov_length(vq->iov, in);
 > >  > > -		/* Sanity check */
 > >  > > -		if (!len) {
 > >  > > -			vq_err(vq, "Unexpected header len for RX: "
 > >  > > -			       "%zd expected %zd\n",
 > >  > > -			       iov_length(vq->hdr, s), hdr_size);
 > >  > > -			break;
 > >  > > -		}
 > >  > > -		err = sock->ops->recvmsg(NULL, sock, &msg,
 > >  > > -					 len, MSG_DONTWAIT | MSG_TRUNC);
 > >  > > -		/* TODO: Check specific error and bomb out unless EAGAIN? */
 > >  > > -		if (err < 0) {
 > >  > > -			vhost_discard_vq_desc(vq, 1);
 > >  > > -			break;
 > >  > > -		}
 > >  > > -		/* TODO: Should check and handle checksum. */
 > >  > > -		if (err > len) {
 > >  > > -			pr_debug("Discarded truncated rx packet: "
 > >  > > -				 " len %d > %zd\n", err, len);
 > >  > > -			vhost_discard_vq_desc(vq, 1);
 > >  > > -			continue;
 > >  > > -		}
 > >  > > -		len = err;
 > >  > > -		err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size);
 > >  > > -		if (err) {
 > >  > > -			vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n",
 > >  > > -			       vq->iov->iov_base, err);
 > >  > > -			break;
 > >  > > -		}
 > >  > > -		len += hdr_size;
 > >  > > -		vhost_add_used_and_signal(&net->dev, vq, head, len);
 > >  > > -		if (unlikely(vq_log))
 > >  > > -			vhost_log_write(vq, vq_log, log, len);
 > >  > > -		total_len += len;
 > >  > > -		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 > >  > > -			vhost_poll_queue(&vq->poll);
 > >  > > -			break;
 > >  > > -		}
 > >  > > -	}
 > >  > > -
 > >  > > -	mutex_unlock(&vq->mutex);
 > >  > > -}
 > >  > > -
 > >  > > -/* Expects to be always run from workqueue - which acts as
 > >  > > - * read-size critical section for our kind of RCU. */
 > >  > > -static void handle_rx_mergeable(struct vhost_net *net)
 > >  > > +static void handle_rx(struct vhost_net *net)
 > >  > >  {
 > >  > >  	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 > >  > >  	unsigned uninitialized_var(in), log;
 > >  > > @@ -431,7 +324,8 @@ static void handle_rx_mergeable(struct vhost_net *net)
 > >  > >  		sock_len += sock_hlen;
 > >  > >  		vhost_len = sock_len + vhost_hlen;
 > >  > >  		headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 > >  > > -					&in, vq_log, &log);
 > >  > > +					&in, vq_log, &log,
 > >  > > +					likely(mergeable) ? UIO_MAXIOV : 1);
 > >  > >  		/* On error, stop handling until the next kick. */
 > >  > >  		if (unlikely(headcount < 0))
 > >  > >  			break;
 > >  > > @@ -497,14 +391,6 @@ static void handle_rx_mergeable(struct vhost_net *net)
 > >  > >  	mutex_unlock(&vq->mutex);
 > >  > >  }
 > >  > >  
 > >  > > -static void handle_rx(struct vhost_net *net)
 > >  > > -{
 > >  > > -	if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF))
 > >  > > -		handle_rx_mergeable(net);
 > >  > > -	else
 > >  > > -		handle_rx_big(net);
 > >  > > -}
 > >  > > -
 > >  > >  static void handle_tx_kick(struct vhost_work *work)
 > >  > >  {
 > >  > >  	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
--
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diff mbox

Patch

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 95e49de..c32a2e4 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -227,6 +227,7 @@  static int peek_head_len(struct sock *sk)
  * @iovcount	- returned count of io vectors we fill
  * @log		- vhost log
  * @log_num	- log offset
+ * @quota       - headcount quota, 1 for big buffer
  *	returns number of buffer heads allocated, negative on error
  */
 static int get_rx_bufs(struct vhost_virtqueue *vq,
@@ -234,7 +235,8 @@  static int get_rx_bufs(struct vhost_virtqueue *vq,
 		       int datalen,
 		       unsigned *iovcount,
 		       struct vhost_log *log,
-		       unsigned *log_num)
+		       unsigned *log_num,
+		       unsigned int quota)
 {
 	unsigned int out, in;
 	int seg = 0;
@@ -242,7 +244,7 @@  static int get_rx_bufs(struct vhost_virtqueue *vq,
 	unsigned d;
 	int r, nlogs = 0;
 
-	while (datalen > 0) {
+	while (datalen > 0 && headcount < quota) {
 		if (unlikely(seg >= UIO_MAXIOV)) {
 			r = -ENOBUFS;
 			goto err;
@@ -282,116 +284,7 @@  err:
 
 /* Expects to be always run from workqueue - which acts as
  * read-size critical section for our kind of RCU. */
-static void handle_rx_big(struct vhost_net *net)
-{
-	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
-	unsigned out, in, log, s;
-	int head;
-	struct vhost_log *vq_log;
-	struct msghdr msg = {
-		.msg_name = NULL,
-		.msg_namelen = 0,
-		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
-		.msg_controllen = 0,
-		.msg_iov = vq->iov,
-		.msg_flags = MSG_DONTWAIT,
-	};
-
-	struct virtio_net_hdr hdr = {
-		.flags = 0,
-		.gso_type = VIRTIO_NET_HDR_GSO_NONE
-	};
-
-	size_t len, total_len = 0;
-	int err;
-	size_t hdr_size;
-	struct socket *sock = rcu_dereference(vq->private_data);
-	if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
-		return;
-
-	mutex_lock(&vq->mutex);
-	vhost_disable_notify(vq);
-	hdr_size = vq->vhost_hlen;
-
-	vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
-		vq->log : NULL;
-
-	for (;;) {
-		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
-					 ARRAY_SIZE(vq->iov),
-					 &out, &in,
-					 vq_log, &log);
-		/* On error, stop handling until the next kick. */
-		if (unlikely(head < 0))
-			break;
-		/* OK, now we need to know about added descriptors. */
-		if (head == vq->num) {
-			if (unlikely(vhost_enable_notify(vq))) {
-				/* They have slipped one in as we were
-				 * doing that: check again. */
-				vhost_disable_notify(vq);
-				continue;
-			}
-			/* Nothing new?  Wait for eventfd to tell us
-			 * they refilled. */
-			break;
-		}
-		/* We don't need to be notified again. */
-		if (out) {
-			vq_err(vq, "Unexpected descriptor format for RX: "
-			       "out %d, int %d\n",
-			       out, in);
-			break;
-		}
-		/* Skip header. TODO: support TSO/mergeable rx buffers. */
-		s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
-		msg.msg_iovlen = in;
-		len = iov_length(vq->iov, in);
-		/* Sanity check */
-		if (!len) {
-			vq_err(vq, "Unexpected header len for RX: "
-			       "%zd expected %zd\n",
-			       iov_length(vq->hdr, s), hdr_size);
-			break;
-		}
-		err = sock->ops->recvmsg(NULL, sock, &msg,
-					 len, MSG_DONTWAIT | MSG_TRUNC);
-		/* TODO: Check specific error and bomb out unless EAGAIN? */
-		if (err < 0) {
-			vhost_discard_vq_desc(vq, 1);
-			break;
-		}
-		/* TODO: Should check and handle checksum. */
-		if (err > len) {
-			pr_debug("Discarded truncated rx packet: "
-				 " len %d > %zd\n", err, len);
-			vhost_discard_vq_desc(vq, 1);
-			continue;
-		}
-		len = err;
-		err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size);
-		if (err) {
-			vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n",
-			       vq->iov->iov_base, err);
-			break;
-		}
-		len += hdr_size;
-		vhost_add_used_and_signal(&net->dev, vq, head, len);
-		if (unlikely(vq_log))
-			vhost_log_write(vq, vq_log, log, len);
-		total_len += len;
-		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
-			vhost_poll_queue(&vq->poll);
-			break;
-		}
-	}
-
-	mutex_unlock(&vq->mutex);
-}
-
-/* Expects to be always run from workqueue - which acts as
- * read-size critical section for our kind of RCU. */
-static void handle_rx_mergeable(struct vhost_net *net)
+static void handle_rx(struct vhost_net *net)
 {
 	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 	unsigned uninitialized_var(in), log;
@@ -431,7 +324,8 @@  static void handle_rx_mergeable(struct vhost_net *net)
 		sock_len += sock_hlen;
 		vhost_len = sock_len + vhost_hlen;
 		headcount = get_rx_bufs(vq, vq->heads, vhost_len,
-					&in, vq_log, &log);
+					&in, vq_log, &log,
+					likely(mergeable) ? UIO_MAXIOV : 1);
 		/* On error, stop handling until the next kick. */
 		if (unlikely(headcount < 0))
 			break;
@@ -497,14 +391,6 @@  static void handle_rx_mergeable(struct vhost_net *net)
 	mutex_unlock(&vq->mutex);
 }
 
-static void handle_rx(struct vhost_net *net)
-{
-	if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF))
-		handle_rx_mergeable(net);
-	else
-		handle_rx_big(net);
-}
-
 static void handle_tx_kick(struct vhost_work *work)
 {
 	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,