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| author | Michael S. Tsirkin <mst@redhat.com> | 2012-12-06 16:00:18 +0100 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2012-12-06 16:09:18 +0100 |
| commit | cedb9bdce099206290a2bdd02ce47a7b253b6a84 (patch) | |
| tree | e30b69a7b94c6fe30272549f3c3ad6faf10bd37f /drivers/vhost | |
| parent | vhost-net: flush outstanding DMAs on memory change (diff) | |
| download | linux-cedb9bdce099206290a2bdd02ce47a7b253b6a84.tar.xz linux-cedb9bdce099206290a2bdd02ce47a7b253b6a84.zip | |
vhost-net: skip head management if no outstanding
For short packets zerocopy mode adds overhead
of managing heads which isn't necessary: we
could simly update used ring directly
same as with zerocopy disabled.
Things seem to run a bit faster if we detect
and bypass head management when zcopy isn't used.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/vhost')
| -rw-r--r-- | drivers/vhost/net.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 6a86deb39a72..aa76ca72606a 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -241,7 +241,7 @@ static void handle_tx(struct vhost_net *net) size_t hdr_size; struct socket *sock; struct vhost_ubuf_ref *uninitialized_var(ubufs); - bool zcopy; + bool zcopy, zcopy_used; /* TODO: check that we are running from vhost_worker? */ sock = rcu_dereference_check(vq->private_data, 1); @@ -319,8 +319,11 @@ static void handle_tx(struct vhost_net *net) iov_length(vq->hdr, s), hdr_size); break; } + zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN || + vq->upend_idx != vq->done_idx); + /* use msg_control to pass vhost zerocopy ubuf info to skb */ - if (zcopy) { + if (zcopy_used) { vq->heads[vq->upend_idx].id = head; if (!vhost_net_tx_select_zcopy(net) || len < VHOST_GOODCOPY_LEN) { @@ -348,7 +351,7 @@ static void handle_tx(struct vhost_net *net) /* TODO: Check specific error and bomb out unless ENOBUFS? */ err = sock->ops->sendmsg(NULL, sock, &msg, len); if (unlikely(err < 0)) { - if (zcopy) { + if (zcopy_used) { if (ubufs) vhost_ubuf_put(ubufs); vq->upend_idx = ((unsigned)vq->upend_idx - 1) % @@ -362,7 +365,7 @@ static void handle_tx(struct vhost_net *net) if (err != len) pr_debug("Truncated TX packet: " " len %d != %zd\n", err, len); - if (!zcopy) + if (!zcopy_used) vhost_add_used_and_signal(&net->dev, vq, head, 0); else vhost_zerocopy_signal_used(net, vq); |