Commit 8c2e6b26ffe2 ("vhost/net: Defer TX queue re-enable until after
sendmsg") tries to defer the notification enabling by moving the logic
out of the loop after the vhost_tx_batch() when nothing new is spotted.
This caused unexpected side effects as the new logic is reused for
several other error conditions.A previous patch reverted 8c2e6b26ffe2. Now, bring the performance back up by flushing batched buffers before enabling notifications. Link: https://lore.kernel.org/all/[email protected] Reported-by: Jon Kohler <[email protected]> Cc: [email protected] Fixes: 8c2e6b26ffe2 ("vhost/net: Defer TX queue re-enable until after sendmsg") Signed-off-by: Jason Wang <[email protected]> Signed-off-by: Michael S. Tsirkin <[email protected]> --- drivers/vhost/net.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 57efd5c55f89..72ecb8691275 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -782,11 +782,18 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock) 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; - } + } else { + /* Flush batched packets before enabling + * virtqueue notifications to reduce + * unnecessary virtqueue kicks. + */ + vhost_tx_batch(net, nvq, sock, &msg); + + if (unlikely(vhost_enable_notify(&net->dev, + vq))) { + vhost_disable_notify(&net->dev, vq); + continue; + } break; } -- MST
