[dpdk-dev] [PATCH v2] net/virtio: fix an incorrect behavior of device stop/start

[Fischetti, Antonio]

> -----Original Message-----
> From: Bie, Tiwei
> Sent: Tuesday, December 5, 2017 3:12 AM
> To: Fischetti, Antonio <antonio.fischetti at intel.com>
> Cc: dev at dpdk.org; yliu at fridaylinux.org; maxime.coquelin at redhat.com;
> jfreimann at redhat.com; stable at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v2] net/virtio: fix an incorrect behavior
> of device stop/start
> 
> On Mon, Dec 04, 2017 at 07:46:07PM +0800, Fischetti, Antonio wrote:
> > > -----Original Message-----
> > > From: Bie, Tiwei
> > > Sent: Monday, December 4, 2017 7:20 AM
> > > To: Fischetti, Antonio <antonio.fischetti at intel.com>
> > > Cc: dev at dpdk.org; yliu at fridaylinux.org; maxime.coquelin at redhat.com;
> > > jfreimann at redhat.com; stable at dpdk.org
> > > Subject: Re: [dpdk-dev] [PATCH v2] net/virtio: fix an incorrect
> behavior
> > > of device stop/start
> > >
> > > On Sat, Dec 02, 2017 at 12:30:33PM +0800, Tiwei Bie wrote:
> > > > Hi Antonio,
> > > >
> > > > On Sat, Dec 02, 2017 at 01:17:58AM +0800, Fischetti, Antonio
> wrote:
> > > > > Hi All,
> > > > > I've got an update on this.
> > > > > I could replicate the same issue by using testpmd + a VM (=
> Virtual
> > > Machine).
> > > > >
> > > > > The test topology I'm using is:
> > > > >
> > > > >
> > > > > [Traffic gen]----[NIC port #0]----[testpmd]----[vhost port #2]--
> --+
> > > > >
> |
> > > > >
> |
> > > > >
> > > [testpmd in
> > > > >
> the
> > > VM]
> > > > >
> |
> > > > >
> |
> > > > > [Traffic gen]----[NIC port #1]----[testpmd]----[vhost port #3]--
> --+
> > > > >
> > > > >
> > > > > So there's no OvS now in the picture: one testpmd running on the
> > > host
> > > > > and one testpmd running on the VM.
> > > > >
> > > > > The issue is that no packet goes through testpmd in the VM.
> > > > > It seems this is happening after this patch was upstreamed.
> > > > >
> > > > > Please note
> > > > > -----------
> > > > > To replicate this issue both the next 2 conditions must be met:
> > > > >  - the traffic is already being sent before launching testpmd in
> the
> > > VM
> > > > >  - there are at least 2 forwarding lcores.
> > > > >
> > > >
> > > [...]
> > > >
> > > > Do you see anything I missed? Or can you reproduce the issue with
> the
> > > > setup I'm using?
> > > >
> > >
> > > Hi Antonio,
> > >
> > > Are you using vector Rx in your test? After some further
> >
> > [Antonio] Hi Tiwei, yes I suppose so.
> >
> > Below some more details on my testbench to explain why I'm
> > using this configuration.
> >
> > With this topology I can replicate as much as possible
> > my initial OvS-DPDK testbench. In the ovs case I
> > had 1 single process on the host (OvS) which spawns 2
> > dequeuing threads running on 2 different lcores (please
> > note: if they run on the same lcore there's no issue).
> >
> > So in place of Ovs I'm using 1 testpmd only on the host like:
> >
> > sudo ./x86_64-native-linuxapp-gcc/app/testpmd -l 0-3 -n 4 \
> >     --socket-mem=1024,1024 \
> >     --vdev 'eth_vhost0,iface=/tmp/sock0,queues=1' \
> >     --vdev 'eth_vhost1,iface=/tmp/sock1,queues=1' -- -i
> >
> > so the testpmd on the host is seeing 4 phy ports, 2 are real
> > phy ports and 2 are vdev.
> >
> > Then I set the forwarding cores
> >
> >  testpmd> set corelist 2,3
> >
> > and the port order
> >  testpmd> set portlist 0,2,1,3
> >  testpmd> set fwd mac retry
> >  testpmd> start
> >
> > I then launch the VM and inside of it I launch testpmd:
> >
> > ./testpmd -c 0x3 -n 4 --socket-mem 512 -- --burst=64 -i \
> >     --txqflags=0xf00 --disable-hw-vlan
> >
> > on testpmd console:
> >  testpmd> set fwd mac retry
> >  testpmd> start
> >
> > As the traffic is already running at the line-rate for
> > some seconds, for sure all the descs have been consumed.
> >
> > I'm currently using 1 GB hugepage sizes, but I was
> > seeing the same issue with OvS when I was using 2 MB
> > hugepage sizes.
> >
> 
> Hi Antonio,
> 
> Got it! Thank you for the detailed info!
> I will send out a patch to fix this issue ASAP.

[Antonio] That's great Tiwei, thanks! Once it is ready I 
can give it a try as with testpmd as with OvS on the host.


> 
> Best regards,
> Tiwei Bie