Re: [RFC PATCH net-next 04/12] vhost_net: split out datacopy logic
From: Jesse Brandeburg <hidden>
Date: 2018-05-21 16:46:52
Also in:
kvm, lkml, netdev
On Mon, 21 May 2018 17:04:25 +0800 Jason wrote:
quoted hunk ↗ jump to hunk
Instead of mixing zerocopy and datacopy logics, this patch tries to split datacopy logic out. This results for a more compact code and specific optimization could be done on top more easily. Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/vhost/net.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 102 insertions(+), 9 deletions(-)diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 4ebac76..4682fcc 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c@@ -492,9 +492,95 @@ static bool vhost_has_more_pkts(struct vhost_net *net, likely(!vhost_exceeds_maxpend(net)); } +static void handle_tx_copy(struct vhost_net *net) +{ + struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX]; + struct vhost_virtqueue *vq = &nvq->vq; + unsigned out, in;
move "out" and "in" down to inside the for loop as well.
+ int head;
move this "head" declaration inside for-loop below.
+ 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;
+ size_t hdr_size;
+ struct socket *sock;
+ struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
+ int sent_pkts = 0;why do we need so many locals?
+
+ 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);
+
+ hdr_size = nvq->vhost_hlen;
+
+ for (;;) {
+ head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
+ ARRAY_SIZE(vq->iov),
+ &out, &in);
+ /* 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(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);don't break strings, keep all the bits between " " together, even if it is longer than 80 chars.
+ break; + } + + len = init_iov_iter(vq, &msg.msg_iter, hdr_size, out); + if (len < 0) + break;
same comment as previous patch, len is a size_t which is unsigned.
+
+ total_len += len;
+ if (total_len < VHOST_NET_WEIGHT &&
+ vhost_has_more_pkts(net, vq)) {
+ msg.msg_flags |= MSG_MORE;
+ } else {
+ msg.msg_flags &= ~MSG_MORE;
+ }
don't need { } here.
+
+ /* 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);single line " " string please