From: Jason Wang <jasowang@xxxxxxxxxx>
Date: Tue, 29 May 2018 14:18:19 +0800
> After commit e2b3b35eb989 ("vhost_net: batch used ring update in rx"),
> we tend to batch updating used heads. But it doesn't flush batched
> heads before trying to do busy polling, this will cause vhost to wait
> for guest TX which waits for the used RX. Fixing by flush batched
> heads before busy loop.
>
> 1 byte TCP_RR performance recovers from 13107.83 to 50402.65.
>
> Fixes: e2b3b35eb989 ("vhost_net: batch used ring update in rx")
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Applied and queued up for -stable.
