From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tiwei Bie <tiwei.bie@intel.com>
Subject: Re: [PATCH v4 2/3] net/virtio: add packet injection
	method
Date: Sat, 6 Jan 2018 12:41:01 +0800
Message-ID: <20180106044100.o3fgg3mggkap2rc5@debian-xvivbkq.sh.intel.com>
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Cc: Xiao Wang <xiao.w.wang@intel.com>, dev@dpdk.org, yliu@fridaylinux.org
To: Stephen Hemminger <stephen@networkplumber.org>
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On Fri, Jan 05, 2018 at 12:27:37PM -0800, Stephen Hemminger wrote:
> On Thu,  4 Jan 2018 07:59:37 -0800
> Xiao Wang <xiao.w.wang@intel.com> wrote:
> 
> > This patch adds dev_pause, dev_resume and inject_pkts api to allow
> > driver to pause the worker thread and inject special packets into
> > Tx queue. The next patch will be based on this.
> > 
> > Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
> 
> Why is this needed? It isn't obvious what the mechanism is trying to solve.

Xiao needs to use such mechanism to send some special packets
(RARP packet) in the interrupt handler to implement the GUEST
ANNOUNCE feature.

To avoid the contention between user's Tx threads and the
interrupt thread. He needs to pause user's Tx threads (by
reusing the existing 'started' flag in `virtio_hw`) first,
and call tx_burst() to send the RARP packet.

He already provided the pause() and resume() functions, but
the implementation of sending the RARP packet (add a field
named as `rarp_buf` in `virtio_hw`, and check it in tx_burst()
functions) is too specific. So I just suggested him to give
rarp_buf a more generic name and provide a simple wrapper of
tx_burst for internal use:

http://dpdk.org/ml/archives/dev/2018-January/085213.html

Is it OK to you? Or do you have any other suggestions? Thanks!

PS. The latest version is v5, below is the link:
http://dpdk.org/ml/archives/dev/2018-January/085354.html

Best regards,
Tiwei Bie