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Message-Id: <1532045721-4958-7-git-send-email-jasowang@redhat.com>
Date: Fri, 20 Jul 2018 08:15:18 +0800
From: Jason Wang <jasowang@...hat.com>
To: mst@...hat.com, jasowang@...hat.com, netdev@...r.kernel.org
Cc: kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org
Subject: [PATCH net-next 6/9] vhost_net: split out datacopy logic
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@...hat.com>
---
drivers/vhost/net.c | 110 ++++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 90 insertions(+), 20 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f59b615..9cef0b2 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -520,9 +520,7 @@ static bool tx_can_batch(struct vhost_virtqueue *vq, size_t total_len)
!vhost_vq_avail_empty(vq->dev, vq);
}
-/* 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)
+static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
{
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
@@ -537,30 +535,76 @@ static void handle_tx(struct vhost_net *net)
};
size_t len, total_len = 0;
int err;
- struct socket *sock;
- struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
- bool zcopy, zcopy_used;
int sent_pkts = 0;
- mutex_lock(&vq->mutex);
- sock = vq->private_data;
- if (!sock)
- goto out;
+ for (;;) {
+ bool busyloop_intr = false;
- if (!vq_iotlb_prefetch(vq))
- goto out;
+ head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
+ &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);
- vhost_net_disable_vq(net, vq);
+ total_len += len;
+ if (tx_can_batch(vq, total_len))
+ 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)) {
+ 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;
+ }
+ }
+}
- zcopy = nvq->ubufs;
+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 (;;) {
bool busyloop_intr;
/* Release DMAs done buffers first */
- if (zcopy)
- vhost_zerocopy_signal_used(net, vq);
+ vhost_zerocopy_signal_used(net, vq);
busyloop_intr = false;
head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
@@ -579,9 +623,9 @@ static void handle_tx(struct vhost_net *net)
break;
}
- zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
- && !vhost_exceeds_maxpend(net)
- && vhost_net_tx_select_zcopy(net);
+ zcopy_used = len >= VHOST_GOODCOPY_LEN
+ && !vhost_exceeds_maxpend(net)
+ && vhost_net_tx_select_zcopy(net);
/* use msg_control to pass vhost zerocopy ubuf info to skb */
if (zcopy_used) {
@@ -636,6 +680,32 @@ static void handle_tx(struct vhost_net *net)
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:
mutex_unlock(&vq->mutex);
}
--
2.7.4
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