netdev - Re: [PATCH net-next 2/2] vsock/virtio: avoid enqueue packets when work queue is empty

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Date: Fri, 21 Jun 2024 11:47:51 +0200
From: Luigi Leonardi <luigi.leonardi@...look.com>
To: mvaralar@...hat.com
Cc: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	kvm@...r.kernel.org,
	luigi.leonardi@...look.com,
	marco.pinn95@...il.com,
	netdev@...r.kernel.org,
	pabeni@...hat.com,
	sgarzare@...hat.com,
	stefanha@...hat.com,
	virtualization@...ts.linux.dev
Subject: Re: [PATCH net-next 2/2] vsock/virtio: avoid enqueue packets when work queue is empty

Hi Matias,

> > > I think the test can always send packets at a frequency so the worker queue
> > > is always empty. but maybe, this is a corner case and most of the time the
> > > worker queue is not empty in a non-testing environment.
> >
> > I'm not sure about this, but IMHO this optimization is free, there is no
> > penalty for using it, in the worst case the system will work as usual.
> > In any case, I'm more than happy to do some additional testing, do you have
> > anything in mind?
> >
> Sure!, this is very a interesting improvement and I am in favor for
> that! I was only thinking out loud ;)

No worries :)

> I asked previous questions
> because, in my mind, I was thinking that this improvement would trigger
> only for the first bunch of packets, i.e., when the worker queue is
> empty so its effect would be seen "only at the beginning of the
> transmission" until the worker-queue begins to fill. If I understand
> correctly, the worker-queue starts to fill just after the virtqueue is
> full, am I right?

Correct! Packets are enqueued in the worker-queue only if the virtqueue
is full.

Luigi