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Merge branch 'net-vhost-improve-performance-when-enable-busyloop'
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Tonghao Zhang says:

====================
net: vhost: improve performance when enable busyloop

This patches improve the guest receive performance.
On the handle_tx side, we poll the sock receive queue
at the same time. handle_rx do that in the same way.

For more performance report, see patch 4
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller committed Sep 27, 2018
2 parents af4325e + 441abde commit c09c147
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Showing 2 changed files with 92 additions and 79 deletions.
147 changes: 85 additions & 62 deletions drivers/vhost/net.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -480,33 +480,94 @@ static void vhost_tx_batch(struct vhost_net *net,
nvq->batched_xdp = 0;
}

static int sock_has_rx_data(struct socket *sock)
{
if (unlikely(!sock))
return 0;

if (sock->ops->peek_len)
return sock->ops->peek_len(sock);

return skb_queue_empty(&sock->sk->sk_receive_queue);
}

static void vhost_net_busy_poll_try_queue(struct vhost_net *net,
struct vhost_virtqueue *vq)
{
if (!vhost_vq_avail_empty(&net->dev, vq)) {
vhost_poll_queue(&vq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
vhost_disable_notify(&net->dev, vq);
vhost_poll_queue(&vq->poll);
}
}

static void vhost_net_busy_poll(struct vhost_net *net,
struct vhost_virtqueue *rvq,
struct vhost_virtqueue *tvq,
bool *busyloop_intr,
bool poll_rx)
{
unsigned long busyloop_timeout;
unsigned long endtime;
struct socket *sock;
struct vhost_virtqueue *vq = poll_rx ? tvq : rvq;

mutex_lock_nested(&vq->mutex, poll_rx ? VHOST_NET_VQ_TX: VHOST_NET_VQ_RX);
vhost_disable_notify(&net->dev, vq);
sock = rvq->private_data;

busyloop_timeout = poll_rx ? rvq->busyloop_timeout:
tvq->busyloop_timeout;

preempt_disable();
endtime = busy_clock() + busyloop_timeout;

while (vhost_can_busy_poll(endtime)) {
if (vhost_has_work(&net->dev)) {
*busyloop_intr = true;
break;
}

if ((sock_has_rx_data(sock) &&
!vhost_vq_avail_empty(&net->dev, rvq)) ||
!vhost_vq_avail_empty(&net->dev, tvq))
break;

cpu_relax();
}

preempt_enable();

if (poll_rx || sock_has_rx_data(sock))
vhost_net_busy_poll_try_queue(net, vq);
else if (!poll_rx) /* On tx here, sock has no rx data. */
vhost_enable_notify(&net->dev, rvq);

mutex_unlock(&vq->mutex);
}

static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
struct vhost_net_virtqueue *nvq,
struct vhost_net_virtqueue *tnvq,
unsigned int *out_num, unsigned int *in_num,
struct msghdr *msghdr, bool *busyloop_intr)
{
struct vhost_virtqueue *vq = &nvq->vq;
unsigned long uninitialized_var(endtime);
int r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
struct vhost_virtqueue *rvq = &rnvq->vq;
struct vhost_virtqueue *tvq = &tnvq->vq;

int r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
out_num, in_num, NULL, NULL);

if (r == vq->num && vq->busyloop_timeout) {
if (r == tvq->num && tvq->busyloop_timeout) {
/* Flush batched packets first */
if (!vhost_sock_zcopy(vq->private_data))
vhost_tx_batch(net, nvq, vq->private_data, msghdr);
preempt_disable();
endtime = busy_clock() + vq->busyloop_timeout;
while (vhost_can_busy_poll(endtime)) {
if (vhost_has_work(vq->dev)) {
*busyloop_intr = true;
break;
}
if (!vhost_vq_avail_empty(vq->dev, vq))
break;
cpu_relax();
}
preempt_enable();
r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
if (!vhost_sock_zcopy(tvq->private_data))
// vhost_net_signal_used(tnvq);
vhost_tx_batch(net, tnvq, tvq->private_data, msghdr);

vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, false);

r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
out_num, in_num, NULL, NULL);
}

Expand Down Expand Up @@ -856,7 +917,7 @@ static void handle_tx(struct vhost_net *net)
struct vhost_virtqueue *vq = &nvq->vq;
struct socket *sock;

mutex_lock(&vq->mutex);
mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_TX);
sock = vq->private_data;
if (!sock)
goto out;
Expand Down Expand Up @@ -897,58 +958,20 @@ static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
return len;
}

static int sk_has_rx_data(struct sock *sk)
{
struct socket *sock = sk->sk_socket;

if (sock->ops->peek_len)
return sock->ops->peek_len(sock);

return skb_queue_empty(&sk->sk_receive_queue);
}

static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
bool *busyloop_intr)
{
struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *rvq = &rnvq->vq;
struct vhost_virtqueue *tvq = &tnvq->vq;
unsigned long uninitialized_var(endtime);
int len = peek_head_len(rnvq, sk);

if (!len && tvq->busyloop_timeout) {
if (!len && rvq->busyloop_timeout) {
/* Flush batched heads first */
vhost_net_signal_used(rnvq);
/* Both tx vq and rx socket were polled here */
mutex_lock_nested(&tvq->mutex, 1);
vhost_disable_notify(&net->dev, tvq);

preempt_disable();
endtime = busy_clock() + tvq->busyloop_timeout;

while (vhost_can_busy_poll(endtime)) {
if (vhost_has_work(&net->dev)) {
*busyloop_intr = true;
break;
}
if ((sk_has_rx_data(sk) &&
!vhost_vq_avail_empty(&net->dev, rvq)) ||
!vhost_vq_avail_empty(&net->dev, tvq))
break;
cpu_relax();
}

preempt_enable();

if (!vhost_vq_avail_empty(&net->dev, tvq)) {
vhost_poll_queue(&tvq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev, tvq))) {
vhost_disable_notify(&net->dev, tvq);
vhost_poll_queue(&tvq->poll);
}

mutex_unlock(&tvq->mutex);
vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, true);

len = peek_head_len(rnvq, sk);
}
Expand Down Expand Up @@ -1063,7 +1086,7 @@ static void handle_rx(struct vhost_net *net)
__virtio16 num_buffers;
int recv_pkts = 0;

mutex_lock_nested(&vq->mutex, 0);
mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_RX);
sock = vq->private_data;
if (!sock)
goto out;
Expand Down
24 changes: 7 additions & 17 deletions drivers/vhost/vhost.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -294,8 +294,11 @@ static void vhost_vq_meta_reset(struct vhost_dev *d)
{
int i;

for (i = 0; i < d->nvqs; ++i)
for (i = 0; i < d->nvqs; ++i) {
mutex_lock(&d->vqs[i]->mutex);
__vhost_vq_meta_reset(d->vqs[i]);
mutex_unlock(&d->vqs[i]->mutex);
}
}

static void vhost_vq_reset(struct vhost_dev *dev,
Expand Down Expand Up @@ -891,20 +894,6 @@ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
#define vhost_get_used(vq, x, ptr) \
vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)

static void vhost_dev_lock_vqs(struct vhost_dev *d)
{
int i = 0;
for (i = 0; i < d->nvqs; ++i)
mutex_lock_nested(&d->vqs[i]->mutex, i);
}

static void vhost_dev_unlock_vqs(struct vhost_dev *d)
{
int i = 0;
for (i = 0; i < d->nvqs; ++i)
mutex_unlock(&d->vqs[i]->mutex);
}

static int vhost_new_umem_range(struct vhost_umem *umem,
u64 start, u64 size, u64 end,
u64 userspace_addr, int perm)
Expand Down Expand Up @@ -954,7 +943,10 @@ static void vhost_iotlb_notify_vq(struct vhost_dev *d,
if (msg->iova <= vq_msg->iova &&
msg->iova + msg->size - 1 >= vq_msg->iova &&
vq_msg->type == VHOST_IOTLB_MISS) {
mutex_lock(&node->vq->mutex);
vhost_poll_queue(&node->vq->poll);
mutex_unlock(&node->vq->mutex);

list_del(&node->node);
kfree(node);
}
Expand Down Expand Up @@ -986,7 +978,6 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
int ret = 0;

mutex_lock(&dev->mutex);
vhost_dev_lock_vqs(dev);
switch (msg->type) {
case VHOST_IOTLB_UPDATE:
if (!dev->iotlb) {
Expand Down Expand Up @@ -1020,7 +1011,6 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
break;
}

vhost_dev_unlock_vqs(dev);
mutex_unlock(&dev->mutex);

return ret;
Expand Down

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