Re: [PATCH net-next v13 0/5] tun/tap & vhost-net: apply qdisc backpressure on full ptr_ring to reduce TX drops

Simon Schippers <[email protected]> Sun, 2 Aug 2026 11:51:33 +0200
Newsgroups dev.linux.lists.virtualization,org.kernel.vger.kvm,org.kernel.vger.linux-doc,org.kernel.vger.linux-kernel,org.kernel.vger.netdev
Message-ID <[email protected]>
On 7/30/26 23:36, Simon Schippers wrote:
> This patch series deals with tun/tap & vhost-net which drop incoming
> SKBs whenever their internal ptr_ring buffer is full. Instead, with this
> patch series, the associated netdev queue is stopped, but only when the
> new IFF_BACKPRESSURE flag is set and a qdisc is attached. Without the
> flag, or if no qdisc is present, the existing behavior is preserved. The
> XDP transmit path is not affected. This patch series touches tun/tap and
> vhost-net, as they share common logic and must be updated together.
> Modifying only one of them would break the other.

Sashiko found valid regressions, even though the code stayed the same.

I will address them and send a v14 soon.