Re: KVM-74 and network timeout?

[Felix Leimbach <felix.leimbach@gmx.net>]

Sean Mahrt wrote:
> I’ve noticed the guest with a lot of Disk I/O
> (commercial detection) after a while has a lot of NFS timeouts….  Virtio
> or E1000 give me the same result.

I noticed exactly the same problem after moving from kvm-64 on a
2.6.25.3 host to kvm-74 on a 2.6.26.3 host.

Adding to your observations:
- CIFS shares are affected as well: Under heavy traffic I get timeouts
from the server, see [1]
- ne2k_pci and rtl8139 guests seem to be affected as well

> Now the real bad part, I’m getting
> pings in the order of ms, like 20-100ms on a bridged connection… and NFS
> is going crazy...

My pings also increased from < 0.1ms to 16ms when the physical interface
of the bridge was maxed out.
Don't know, whether transferring from VM to VM would also trigger that.

>  I’m using smp on the guests (and the host), and 2.6.25 on the guests…

My guests where UP and mostly Windows Server 2003 and one Gentoo 2.6.26,
so I think the culprit is elsewhere.

> Where should I start looking?  Is this a KVM-74 issue?  Bump to KVM-75?

You might try kvm-64 which is rock-solid for me when paired with a
2.6.25 KVM kernel module.

[1]
Sep 6 17:42:58 kernsrc@obelix CIFS VFS: server not responding
Sep 6 17:42:58 kernsrc@obelix CIFS VFS: No response to cmd 46 mid 30836
Sep 6 17:42:58 kernsrc@obelix CIFS VFS: Send error in read = -11
Sep 6 17:51:28 kernsrc@obelix CIFS VFS: server not responding
Sep 6 17:51:28 kernsrc@obelix CIFS VFS: No response for cmd 50 mid 30850