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vhost_net: split out datacopy logic

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Instead of mixing zerocopy and datacopy logics, this patch tries to
split datacopy logic out. This results for a more compact code and
ad-hoc optimization could be done on top more easily.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2018-07-20 08:15:18 +08:00 committed by David S. Miller
parent c92a8a8cb7
commit 0d20bdf34d
1 changed files with 90 additions and 20 deletions
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110
drivers/vhost/net.c
View file

@ -520,9 +520,7 @@ static bool tx_can_batch(struct vhost_virtqueue *vq, size_t total_len)
!vhost_vq_avail_empty(vq->dev, vq); !vhost_vq_avail_empty(vq->dev, vq);
} }
/* Expects to be always run from workqueue - which acts as static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
* read-size critical section for our kind of RCU. */
static void handle_tx(struct vhost_net *net)
{ {
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX]; struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq; struct vhost_virtqueue *vq = &nvq->vq;
@ -537,30 +535,76 @@ static void handle_tx(struct vhost_net *net)
}; };
size_t len, total_len = 0; size_t len, total_len = 0;
int err; int err;
struct socket *sock;
struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
bool zcopy, zcopy_used;
int sent_pkts = 0; int sent_pkts = 0;
mutex_lock(&vq->mutex); for (;;) {
sock = vq->private_data; bool busyloop_intr = false;
if (!sock)
goto out;
if (!vq_iotlb_prefetch(vq)) head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
goto out; &busyloop_intr);
/* On error, stop handling until the next kick. */
if (unlikely(head < 0))
break;
/* Nothing new? Wait for eventfd to tell us they refilled. */
if (head == vq->num) {
if (unlikely(busyloop_intr)) {
vhost_poll_queue(&vq->poll);
} else if (unlikely(vhost_enable_notify(&net->dev,
vq))) {
vhost_disable_notify(&net->dev, vq);
continue;
}
break;
}
vhost_disable_notify(&net->dev, vq); total_len += len;
vhost_net_disable_vq(net, vq); if (tx_can_batch(vq, total_len))
msg.msg_flags |= MSG_MORE;
else
msg.msg_flags &= ~MSG_MORE;
zcopy = nvq->ubufs; /* TODO: Check specific error and bomb out unless ENOBUFS? */
err = sock->ops->sendmsg(sock, &msg, len);
if (unlikely(err < 0)) {
vhost_discard_vq_desc(vq, 1);
vhost_net_enable_vq(net, vq);
break;
}
if (err != len)
pr_debug("Truncated TX packet: len %d != %zd\n",
err, len);
vhost_add_used_and_signal(&net->dev, vq, head, 0);
if (vhost_exceeds_weight(++sent_pkts, total_len)) {
vhost_poll_queue(&vq->poll);
break;
}
}
}
static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
{
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
unsigned out, in;
int head;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
.msg_control = NULL,
.msg_controllen = 0,
.msg_flags = MSG_DONTWAIT,
};
size_t len, total_len = 0;
int err;
struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
bool zcopy_used;
int sent_pkts = 0;
for (;;) { for (;;) {
bool busyloop_intr; bool busyloop_intr;
/* Release DMAs done buffers first */ /* Release DMAs done buffers first */
if (zcopy) vhost_zerocopy_signal_used(net, vq);
vhost_zerocopy_signal_used(net, vq);
busyloop_intr = false; busyloop_intr = false;
head = get_tx_bufs(net, nvq, &msg, &out, &in, &len, head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
@ -579,9 +623,9 @@ static void handle_tx(struct vhost_net *net)
break; break;
} }
zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN zcopy_used = len >= VHOST_GOODCOPY_LEN
&& !vhost_exceeds_maxpend(net) && !vhost_exceeds_maxpend(net)
&& vhost_net_tx_select_zcopy(net); && vhost_net_tx_select_zcopy(net);
/* use msg_control to pass vhost zerocopy ubuf info to skb */ /* use msg_control to pass vhost zerocopy ubuf info to skb */
if (zcopy_used) { if (zcopy_used) {
@ -636,6 +680,32 @@ static void handle_tx(struct vhost_net *net)
break; break;
} }
} }
}
/* Expects to be always run from workqueue - which acts as
* read-size critical section for our kind of RCU. */
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 socket *sock;
mutex_lock(&vq->mutex);
sock = vq->private_data;
if (!sock)
goto out;
if (!vq_iotlb_prefetch(vq))
goto out;
vhost_disable_notify(&net->dev, vq);
vhost_net_disable_vq(net, vq);
if (vhost_sock_zcopy(sock))
handle_tx_zerocopy(net, sock);
else
handle_tx_copy(net, sock);
out: out:
mutex_unlock(&vq->mutex); mutex_unlock(&vq->mutex);
} }