OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.


Help: OASIS Mailing Lists Help | MarkMail Help

virtio-dev message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]

Subject: Re: [virtio-dev] [PATCH v4] content: Introduce VIRTIO_NET_F_STANDBY feature

On 11/26/2018 7:43 AM, Sameeh Jubran wrote:
On Mon, Nov 26, 2018 at 5:13 PM Sameeh Jubran <sameeh@daynix.com> wrote:
On Thu, Nov 22, 2018 at 8:27 PM Michael S. Tsirkin <mst@redhat.com> wrote:
On Wed, Nov 21, 2018 at 10:04:53PM +0200, Sameeh Jubran wrote:
On Wed, Nov 21, 2018 at 8:41 PM Michael S. Tsirkin <mst@redhat.com> wrote:
Great to see you making progress on this!
Some comments below:

On Wed, Nov 21, 2018 at 05:39:38PM +0200, Sameeh Jubran wrote:
I have created a setup which has two hosts (host A and host B) with X710 10G
cards connected back to back. On one host (I'll refer to this host as host A) I
have configured a bridge with the PF interface as well as vitio-net's interface
(standby) both attached to it.

The command line I used:

/root/qemu/x86_64-softmmu/qemu-system-x86_64 \
-netdev tap,id=hostnet0,script=world_bridge_standalone.sh,downscript=no,ifname=
cc17 \
-device e1000,netdev=hostnet0,mac=56:cc:c1:01:cc:21,id=cc17 \
What's e1000 doing here?
Can this be reason you can not talk to host?
I don't think so, the e1000 is for enabling WAN connection on the
guest for downloading packages and ssh connection. It is connected to
a separate bridge which is connected to the external interface of the
-netdev tap,vhost=on,id=hostnet1,script=test_bridge_standalone.sh,downscript=
no,ifname=cc1_72,queues=4 \
-device virtio-net,host_mtu=1500,netdev=hostnet1,mac=8a:f7:20:29:3b:cb,id=
cc1_72,vectors=10,mq=on,primary=cc1_71 \
-device vfio-pci,host=65:02.1,id=cc1_71,standby=cc1_72 \
-enable-kvm \
-name netkvm \
-m 3000M \
-drive file=/dev/shm/fedora_29.qcow2,if=ide,id=drivex \
-smp 4 \
-vga qxl \
-spice port=6110,disable-ticketing \
-device virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0,addr=0x7 \
-chardev spicevmc,name=vdagent,id=vdagent \
-device virtserialport,nr=1,bus=virtio-serial0.0,chardev=vdagent,name=
com.redhat.spice.0 \
-chardev socket,path=/tmp/qga.sock,server,nowait,id=qga0 \
-device virtio-serial \
-device virtserialport,chardev=qga0,name=org.qemu.guest_agent.0 \
-monitor stdio


Since I couldn't ping from VM to host B, I did an iperf test between the VM and
host A with the feature enabled and during the test I have unplugged the sriov
device, the device was unplugged successfully and no drops where observed as
you can see in the results below:

[root@dhcp156-44 ~]# ifconfig
Well I suspect this won't tell you anything, this shows packet drops at
the hardware level. When e.g. link is down linux won't send any packets
out. The simplest test is to monitor latency and throughput and see that
while it is lower for the duration of migration, there are no huge
spikes around the switch.
Oh, okay will do that.

I have noticed some nasty lag when I tried to ssh to the VM using the
failover interface while I didn't experience that with the e1000.
Sridhar Any idea what might be the cause?
Try tcpdump?
I have investigated this and this is what I have so far, maybe you can
help me with some insights to figure what's going on.
The setup is as follows:

|host A|----X710---------back-to-back--------X710---|host B|

- On the host A:

I have the following interfaces attached to the "test_br0" bridge:

virtio-net's netdev, cc1_72
X710 device PF interfaces: ens2f0 and ens2f1 (only ens2f0 is connected
in the back to back setup)

The bridge has the mac address of the PF ens2f0 and ip :
- On the host B:

I have the following interfaces attached to the "test_br0" bridge:

X710 device PF interfaces: ens2f0 and ens2f1 (only ens2f0 is connected
in the back to back setup)

The bridge has the mac address of the PF ens2f0 and ip :
- On the VM:
The failover interface has the ip:

I can successfully ping 118 from 17. (host B from the VM), however I
can't see the ICMP requests on host A anywhere!
I can see them inside host B on ens2f0, I can see them in the VM on
the failover interface but not on Host A.
Not on the brdige (test_br0) as I would expect, not on the ens2f0
interface, not co cc1_72 (virtio-net) interface and of-course not on
the world interface.

This is the expected behavior when VF is directly attached to the VM and is
being used as the primary interface. You don't see any packets on Host A.

This leads me to think that the icmp requests are send on the "vf"
interface which I cant see on the host. The thing that further
confirms my theory is when
I use device_del to unplug the primary interface, the ping get
disconnected. Using tcpdump I can see that the ping requests arrive to
host B and there is a
suitable ping reply, however the reply is not present on Host A or the
VM anywhere, moreover, when the primary gets disconnected I start
seeing the ping
requests on Host A on the "test_br0" and "ens2f0".

Liran do you think this is related to the mac vtables and vfs issue
that you've mentioned on the monthly meeting?

I have just set the vf mac's address to 0 (ip link set ens2f0 vf 1 mac
00:00:00:00:00:00) after unplugging it (the primary device) and the
pings started working again on the failover interface. So it seems
like the frames were arriving to the vf on the host.

Yes. When the VF is unplugged, you need to reset the VFs MAC so that the packets
with VMs MAC start flowing via VF, bridge and the virtio interface.

Have you looked at this documentation that shows a sample script to initiate live


[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]