Extreme console latency during disk IO (8.0-RC1, previous releases also affected according to others)

[Ivan Voras]

Larry Rosenman wrote:
> On Tue, 13 Oct 2009, Ivan Voras wrote:

>> As for what data is needed, it depends on what you can get - from this
>> discussion thread it looks like it would be enough to verify that disk
>> IO doesn't leave VM processes waiting (i.e. that disk IO doesn't
>> interfere with CPU-bound or idle virtual machines). Though now when I
>> think of it - doesn't Linux ATA driver poll IO in some funky way,
>> expecting to get lower latency that way?
>>
> Have you looked at the information available via the performance tab(s) 
> in the
> client pointing at the ESXi server?

The 20 second time resolution I get in performance charts isn't nearly 
enough to diagnose something like this.

I've now been running iostat in the virtual console (not ssh) during 
disk IO and I can't seem to get the characteristic "stutter" / pause 
behaviour so I think that it's very likely there is too much going on in 
the VM software to accurately conclude anything.