On 2018年05月22日 00:39, Jesse Brandeburg wrote:
On Mon, 21 May 2018 17:04:24 +0800 Jason wrote:
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
drivers/vhost/net.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index de544ee..4ebac76 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -485,6 +485,13 @@ static bool vhost_exceeds_weight(int pkts, int total_len)
unlikely(pkts >= VHOST_NET_PKT_WEIGHT);
}
+static bool vhost_has_more_pkts(struct vhost_net *net,
+ struct vhost_virtqueue *vq)
+{
+ return !vhost_vq_avail_empty(&net->dev, vq) &&
+ likely(!vhost_exceeds_maxpend(net));
This really seems like mis-use of likely/unlikely, in the middle of a
sequence of operations that will always be run when this function is
called. I think you should remove the likely from this helper,
especially, and control the branch from the branch point.
Yes, so I'm consider to make it a macro in next version.
+}
+
/* 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)
@@ -578,8 +585,7 @@ static void handle_tx(struct vhost_net *net)
}
total_len += len;
if (total_len < VHOST_NET_WEIGHT &&
- !vhost_vq_avail_empty(&net->dev, vq) &&
- likely(!vhost_exceeds_maxpend(net))) {
+ vhost_has_more_pkts(net, vq)) {
Yes, I know it came from here, but likely/unlikely are for branch
control, so they should encapsulate everything inside the if, unless
I'm mistaken.
Ok.
msg.msg_flags |= MSG_MORE;
} else {
msg.msg_flags &= ~MSG_MORE;
@@ -605,7 +611,7 @@ static void handle_tx(struct vhost_net *net)
else
vhost_zerocopy_signal_used(net, vq);
vhost_net_tx_packet(net);
- if (unlikely(vhost_exceeds_weight(++sent_pkts, total_len))) {
+ if (vhost_exceeds_weight(++sent_pkts, total_len)) {
You should have kept the unlikely here, and not had it inside the
helper (as per the previous patch. Also, why wasn't this change part
of the previous patch?
Yes, will squash the above into previous one.
Thanks
vhost_poll_queue(&vq->poll);
break;
}
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