That's a good question :)
** Changed in: qemu-kvm (Ubuntu)
Importance: Undecided = Medium
** Changed in: qemu-kvm (Ubuntu)
Status: New = Confirmed
** Changed in: iperf (Ubuntu)
Importance: Undecided = Medium
** Changed in: iperf (Ubuntu)
Status: New = Confirmed
--
You
It would be worth testing this with a container in place of a kvm VM.
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https://bugs.launchpad.net/bugs/1079212
Title:
network slow when 2 VMs using virtio net
Yes, it seems a lot like an iperf bug.
I did the same test with uperf and got full bandwith. Even bonding works well:
ubuntu5# bmon
# Interface RX Rate RX # TX Rate TX #
---
ubuntu5 (source: local)
0 br2
** Changed in: linux (Ubuntu)
Importance: Undecided = Medium
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https://bugs.launchpad.net/bugs/1079212
Title:
network slow when 2 VMs using virtio net bridged to
Thanks for the effort to try to reproduce this.
Yes, vmhost_net is loaded.
ubuntu5# lsmod
Module Size Used by
vhost_net 31873 3
macvtap18293 1 vhost_net
macvlan19002 1 macvtap
ipmi_devintf 17521 0
ipmi_si
What could you have done differently?
- Did you run 2 VMs at the same time?
- Is networking on your VMs using virtio?
- Did you start iperf -s on both VMs?
- Did you use iperf with -d option on two remote hosts to connect to the VMs?
- Are all hosts (KVM hypervisor, and both remote hosts)
Quoting ITec (1079...@bugs.launchpad.net):
Thanks for the .xml. Nothing stands out there...
What could you have done differently?
The main thing is that I used raring, not quantal. This could be
somethign which was fixed in either qemu or the kernel.
- Did you run 2 VMs at the same time?
Was able to easily reproduce this now with just 'iperf -c ip -d.
When I ran your longer loop before it never seemed to happen. I believe
'-n 10' just made it transfer more data, which smoothed over the
inequities here.
[ ID] Interval Transfer Bandwidth
[ 5] 0.0-10.0 sec 20.5 MBytes
Actually, it seems like this might be an iperf bug. The man page
specifically says:
The threading implementation is rather heinous.
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** Also affects: iperf (Ubuntu)
Importance: Undecided
Status: New
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You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1079212
Title:
network slow when 2 VMs using virtio net
I tried to reproduce this on a raring host I had handy and could not.
The throughput definately varied, but was not consistently lopsided.
This doesn't mean it is not present in quantal, or that I didn't do
something different from you.
Is the vhost_net kernel module loaded? Could you please
Since I do not have direct access to the internet on that machine, I had to do:
apport-cli -f -p linux; apport-cli -f -p qemu-kvm
** Attachment added: apport.qemu-kvm
https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1079212/+attachment/3435401/+files/apport.qemu-kvm.n_27o0.apport
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** Attachment added: apport.linux
https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1079212/+attachment/3435402/+files/apport.linux-image-3.5.0-18-generic.a5kfg4.apport
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** Also affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags added: kvm-linux
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https://bugs.launchpad.net/bugs/1079212
Title:
network slow
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