Hello,
I have some problem with poor network performance on libvirt with qemu and
openvswitch.
I’m using libvirt 1.3.1, qemu 2.5 and openvswitch 2.6.0 on Ubuntu 16.04
currently.
My connection diagram looks like below:
+---------------------------+
+---------------------------+ |
Net namespace |
+------------------+ | OVS bridge |
| |
| | | |
| |
| VM | | |
| |
| | +----+---+ +----+-----+
+----+---+ |
| +------+tap dev | | veth A +---------+
veth B | |
| | +--------+ +----------+
+--------+ |
| iperf
-s<---------------------------------------------------------------------------+iperf
-c |
| | | |
| |
+------------------+ | |
| |
| | |
|
+---------------------------+
+---------------------------+
I haven’t got any QoS in tc configured on any interface. When I do this iperf
test I have something about 150Mbps only. IMHO it should be something about
20-30 Gbps there.
Other strange thing is that if I made more such VMS (each connected in same
way, with own OVS bridge and own namespace) bandwidth is lower for each of them
and it looks for me that summarize bandwidth is then something about 1Gbps (30
VMs - each got something about 30Mbps in such test).
When I removed VM and added „tap dev” as internal port in OVS and made same
test, then I had result about 30 Gbps.
I have no idea what can be wrong there. Maybe someone of You had such problems
earlier?
One more thing, on different host with Ubuntu 14.04, OVS 2.0.2, Libvirt 1.3.1
and qemu 2.3 I don’t have this problem.
Kernel on both hosts is 4.4.0 (from Ubuntu repo).
We also found that on Ubuntu 16.04 and OVS 2.6.0 something strange:
2017-05-12T14:22:04.350Z|00120|poll_loop|INFO|wakeup due to [POLLIN] on fd 149
(AF_PACKET(tap27903b5e-06)(protocol=0x3)<->) at ../lib/netdev-linux.c:1139 (86%
CPU usage)
2017-05-12T14:22:04.350Z|00121|poll_loop|INFO|wakeup due to [POLLIN] on fd 149
(AF_PACKET(tap27903b5e-06)(protocol=0x3)<->) at ../lib/netdev-linux.c:1139 (86%
CPU usage)
2017-05-12T14:22:04.351Z|00122|poll_loop|INFO|wakeup due to [POLLIN] on fd 149
(AF_PACKET(tap27903b5e-06)(protocol=0x3)<->) at ../lib/netdev-linux.c:1139 (86%
CPU usage)
2017-05-12T14:22:04.351Z|00123|poll_loop|INFO|wakeup due to [POLLIN] on fd 149
(AF_PACKET(tap27903b5e-06)(protocol=0x3)<->) at ../lib/netdev-linux.c:1139 (86%
CPU usage)
2017-05-12T14:22:04.351Z|00124|poll_loop|INFO|wakeup due to [POLLIN] on fd 149
(AF_PACKET(tap27903b5e-06)(protocol=0x3)<->) at ../lib/netdev-linux.c:1139 (86%
CPU usage)
2017-05-12T14:22:04.351Z|00125|poll_loop|INFO|wakeup due to [POLLIN] on fd 149
(AF_PACKET(tap27903b5e-06)(protocol=0x3)<->) at ../lib/netdev-linux.c:1139 (86%
CPU usage)
We also noticed that during network speed test ovs-vswitchd process is running
all time on 100% CPU (one process always).
Can it be some bug in OVS?
Pozdrawiam / Best regards
Sławek Kapłoński
[email protected]
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