From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: "Yang, Zhiyong" <zhiyong.yang@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>
Subject: Re: [dpdk-dev] [PATCH 0/2] net/virtio: support to turn on/off the traffic flow
Date: Wed, 19 Apr 2017 10:03:19 +0800 [thread overview]
Message-ID: <20170419020319.GQ7333@yliu-dev.sh.intel.com> (raw)
In-Reply-To: <E182254E98A5DA4EB1E657AC7CB9BD2A3EBA60BE@BGSMSX101.gar.corp.intel.com>
On Mon, Apr 17, 2017 at 08:50:52AM +0000, Yang, Zhiyong wrote:
> Hi, yuanhan:
> Sorry for the delay reply due to my annual leave.
>
> > -----Original Message-----
> > From: Yuanhan Liu [mailto:yuanhan.liu@linux.intel.com]
> > Sent: Thursday, April 6, 2017 12:00 PM
> > To: Yang, Zhiyong <zhiyong.yang@intel.com>
> > Cc: dev@dpdk.org; maxime.coquelin@redhat.com
> > Subject: Re: [PATCH 0/2] net/virtio: support to turn on/off the traffic flow
> >
> > On Fri, Mar 31, 2017 at 07:40:17PM +0800, Zhiyong Yang wrote:
> > > Current dpdk code virtio_dev_stop only disables interrupt and marks
> > > link down, When it is invoked, tx/rx traffic flows still work. This is a strange
> > behavior.
> > > The patchset supports the switch of flow by calling virtio_dev_start/stop.
> > >
> > > The implementation refers to vhost pmd.
> >
> > That's a difference story. Vhost pmd uses 2 vars to track the status, whereas you
> > are using only one here. So why not setting/clearing "started" at dev_start/stop,
> > respectively?
> > Then we can check "started" at Rx/Tx functions.
>
> Yes, I use only one var since I think vhost pmd using two is too complex and it is unnecessary.
No, it's needed. For vhost-user pmd, we can only do Rx when both below
items are met:
- port is started
- new_device() is invoked, aka, the device is connected
For that reason, two vars is used to track it.
> I'm setting/clearing started at virtio_dev_start/stop, update_queuing_status is added to avoid
> duplicate code.
It's not about duplicate code. While we could make the var per-device,
you make it per-queue. That's complex and unnecessary.
> I don't understand your question.
>
> >
> > BTW, why does it have to be atomic?
> >
>
> Consider again. It is not necessary to use atomic here. But It seems that it doesn't have an negative effect.
Hmm... that's a good reason to keep it, just because it has no negative
effect? Talking about the negative effect, badly, it really has. The
atomic is more expensive.
--yliu
next prev parent reply other threads:[~2017-04-19 2:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-31 11:40 Zhiyong Yang
2017-03-31 11:40 ` [dpdk-dev] [PATCH 1/2] net/virtio: add data elements to turn on/off " Zhiyong Yang
2017-04-19 6:29 ` [dpdk-dev] [PATCH v2] net/virtio: support " Zhiyong Yang
2017-04-26 7:45 ` Maxime Coquelin
2017-04-26 7:56 ` Yuanhan Liu
2017-04-26 8:02 ` Maxime Coquelin
2017-03-31 11:40 ` [dpdk-dev] [PATCH 2/2] net/virtio: support to turn on/off the " Zhiyong Yang
2017-04-06 3:59 ` [dpdk-dev] [PATCH 0/2] " Yuanhan Liu
2017-04-17 8:50 ` Yang, Zhiyong
2017-04-19 2:03 ` Yuanhan Liu [this message]
2017-04-19 2:31 ` Yang, Zhiyong
2017-04-19 2:58 ` Yuanhan Liu
2017-04-19 5:27 ` Yang, Zhiyong
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