linux-kernel - Re: [PATCH net-next v5 0/8] TUN/TAP & vhost_net: netdev queue flow control to avoid ptr

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Message-ID: <20250924031105-mutt-send-email-mst@kernel.org>
Date: Wed, 24 Sep 2025 03:18:38 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Simon Schippers <simon.schippers@...dortmund.de>
Cc: willemdebruijn.kernel@...il.com, jasowang@...hat.com,
	eperezma@...hat.com, stephen@...workplumber.org, leiyang@...hat.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	virtualization@...ts.linux.dev, kvm@...r.kernel.org
Subject: Re: [PATCH net-next v5 0/8] TUN/TAP & vhost_net: netdev queue flow
 control to avoid ptr_ring tail drop

On Tue, Sep 23, 2025 at 12:15:45AM +0200, Simon Schippers wrote:
> This patch series deals with TUN, TAP and 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 before this happens. 
> This allows the connected qdisc to function correctly as reported by [1] 
> and improves application-layer performance, see our paper [2]. Meanwhile 
> the theoretical performance differs only slightly:


About this whole approach.
What if userspace is not consuming packets?
Won't the watchdog warnings appear?
Is it safe to allow userspace to block a tx queue
indefinitely?

-- 
MST