netdev - RE: [PATCH RFC v4 net-next 0/5] virtio

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Date:	Tue, 2 Dec 2014 10:00:06 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Jason Wang' <jasowang@...hat.com>,
	"Michael S. Tsirkin" <mst@...hat.com>
CC:	"virtualization@...ts.linux-foundation.org" 
	<virtualization@...ts.linux-foundation.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"pagupta@...hat.com" <pagupta@...hat.com>
Subject: RE: [PATCH RFC v4 net-next 0/5] virtio_net: enabling tx interrupts

From: Jason Wang
> > On Mon, Dec 01, 2014 at 06:17:03PM +0800, Jason Wang wrote:
> >>  Hello:
> >>
> >>  We used to orphan packets before transmission for virtio-net. This
> >> breaks
> >>  socket accounting and can lead serveral functions won't work, e.g:
> >>
> >>  - Byte Queue Limit depends on tx completion nofication to work.
> >>  - Packet Generator depends on tx completion nofication for the last
> >>    transmitted packet to complete.
> >>  - TCP Small Queue depends on proper accounting of sk_wmem_alloc to
> >> work.
> >>
> >>  This series tries to solve the issue by enabling tx interrupts. To
> >> minize
> >>  the performance impacts of this, several optimizations were used:
> >>
> >>  - In guest side, virtqueue_enable_cb_delayed() was used to delay the tx
> >>    interrupt untile 3/4 pending packets were sent.

Doesn't that give problems for intermittent transmits?

...

	David