[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] Network shutdown under load
From: |
Tom Lendacky |
Subject: |
[Qemu-devel] Network shutdown under load |
Date: |
Fri, 29 Jan 2010 14:06:41 -0600 |
User-agent: |
KMail/1.12.4 (Linux/2.6.30.10-105.2.4.fc11.i686.PAE; KDE/4.3.4; i686; ; ) |
There's been some discussion of this already in the kvm list, but I want to
summarize what I've found and also include the qemu-devel list in an effort to
find a solution to this problem.
Running a netperf test between two kvm guests results in the guest's network
interface shutting down. I originally found this using kvm guests on two
different machines that were connected via a 10GbE link. However, I found
this problem can be easily reproduced using two guests on the same machine.
I am running the 2.6.32 level of the kvm.git tree and the 0.12.1.2 level of
the qemu-kvm.git tree.
The setup includes two bridges, br0 and br1.
The commands used to start the guests are as follows:
usr/local/bin/qemu-system-x86_64 -name cape-vm001 -m 1024 -drive
file=/autobench/var/tmp/cape-vm001-
raw.img,if=virtio,index=0,media=disk,boot=on -net
nic,model=virtio,vlan=0,macaddr=00:16:3E:00:62:51,netdev=cape-vm001-eth0 -
netdev tap,id=cape-vm001-eth0,script=/autobench/var/tmp/ifup-kvm-
br0,downscript=/autobench/var/tmp/ifdown-kvm-br0 -net
nic,model=virtio,vlan=1,macaddr=00:16:3E:00:62:D1,netdev=cape-vm001-eth1 -
netdev tap,id=cape-vm001-eth1,script=/autobench/var/tmp/ifup-kvm-
br1,downscript=/autobench/var/tmp/ifdown-kvm-br1 -vnc :1 -monitor
telnet::5701,server,nowait -snapshot -daemonize
usr/local/bin/qemu-system-x86_64 -name cape-vm002 -m 1024 -drive
file=/autobench/var/tmp/cape-vm002-
raw.img,if=virtio,index=0,media=disk,boot=on -net
nic,model=virtio,vlan=0,macaddr=00:16:3E:00:62:61,netdev=cape-vm002-eth0 -
netdev tap,id=cape-vm002-eth0,script=/autobench/var/tmp/ifup-kvm-
br0,downscript=/autobench/var/tmp/ifdown-kvm-br0 -net
nic,model=virtio,vlan=1,macaddr=00:16:3E:00:62:E1,netdev=cape-vm002-eth1 -
netdev tap,id=cape-vm002-eth1,script=/autobench/var/tmp/ifup-kvm-
br1,downscript=/autobench/var/tmp/ifdown-kvm-br1 -vnc :2 -monitor
telnet::5702,server,nowait -snapshot -daemonize
The ifup-kvm-br0 script takes the (first) qemu created tap device and brings
it up and adds it to bridge br0. The ifup-kvm-br1 script take the (second)
qemu created tap device and brings it up and adds it to bridge br1.
Each ethernet device within a guest is on it's own subnet. For example:
guest 1 eth0 has addr 192.168.100.32 and eth1 has addr 192.168.101.32
guest 2 eth0 has addr 192.168.100.64 and eth1 has addr 192.168.101.64
On one of the guests run netserver:
netserver -L 192.168.101.32 -p 12000
On the other guest run netperf:
netperf -L 192.168.101.64 -H 192.168.101.32 -p 12000 -t TCP_STREAM -l 60 -c
-C -- -m 16K -M 16K
It may take more than one netperf run (I find that my second run almost always
causes the shutdown) but the network on the eth1 links will stop working.
I did some debugging and found that in qemu on the guest running netserver:
- the receive_disabled variable is set and never gets reset
- the read_poll event handler for the eth1 tap device is disabled and never
re-enabled
These conditions result in no packets being read from the tap device and sent
to the guest - effectively shutting down the network. Network connectivity
can be restored by shutting down the guest interfaces, unloading the
virtio_net module, re-loading the virtio_net module and re-starting the guest
interfaces.
I'm continuing to work on debugging this, but would appreciate if some folks
with more qemu network experience could try to recreate and debug this.
If my kernel config matters, I can provide that.
Thanks,
Tom
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- [Qemu-devel] Network shutdown under load,
Tom Lendacky <=