Strange load issue with 2.4.17

[Simon Matter]

> --On 13. Oktober 2014 17:35:25 +0200 Simon Matter <simon.matter at invoca.ch>
> wrote:
>
>>> Hi,
>>>
>>> for the last week we have seen strange load issues on our Cyrus server.
>>> All
>>> of a sudden the load increases to several thousands, user CPU goes down
>>> to basically zero, system CPU spikes. In the past we've had trouble
>>> with
>>> poor I/O performance, but that went along with an increase in Wait I/O.
>>> We don't
>>> see that now. vmstat shows a massive increase in context switches. When
>>> the
>>> system reaches this state, all we can do is restart Cyrus or reboot the
>>> machine if that doesn't work anymore.
>>>
>>> I'm attaching a Ganglia screenshot that shows the problem clearly. When
>>> the
>>> problem exists, there's not much we can do to analyze it. A colleague
>>> suggested that what we see could be related to this bug:
>>>
>>> https://bugzilla.cyrusimap.org/show_bug.cgi?id=3744
>>>
>>> It was reported for 2.4.16, and it sounds as if it has been fixed, but
>>> is
>>> that fix really part of 2.4.17? Any other ideas?
>>
>> Is this a physical host or running virtualized?
>
> It's virtualized, but it's been that way for more than a year.

Is this by any chance running on KVM, maybe on an AMD cpu?