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/20250915024703.2206-2-jasowang@redhat.com Reported-by: Jon Kohler jon@nutanix.com Cc: stable@vger.kernel.org Fixes: 8c2e6b26ffe2 ("vhost/net: Defer TX queue re-enable until after sendmsg") Signed-off-by: Jason Wang jasowang@redhat.com Signed-off-by: Michael S. Tsirkin mst@redhat.com --- 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; }