Re: Limited IOP/s on Dual Xeon KVM Host

[Stefan Priebe <s.priebe@profihost.ag>]

Am 10.11.2012 17:00, schrieb Andrey Korolyov:
>>> If you mean underlying node, it could be remote memory access or if you
>>> are on a last gen xeon if you have dual io hubs, you could be hitting a
>>> remote io hub for the network card.  I wouldn't think that would cause
>>> such a big hit, but those are things to look into.
>>
>>
>> I'm on E5-Xeon. What means io hub?
>
> QPI path length, in other terms, numa distance(hope Mark means the
> same). Yes, it is impossible to have such degradation even in worst
> case on two-head node. I assume two possible things - you have pinned
> many processes on the core set which including default core for the
> network card` irq, please check it via /proc/interrupts
The 10GBE card is alligned with all it's queues to one CPU. (use intel 
irq affinity script).

> not really did pinning and qemu process losing ticks by switching
> cores - it may be checked, say, by top and guest cpu bencmark. For the
> network card, it may be generally recommended to move its irq affinity
> to entire numa node to which it belongs.
Might be but i'm seeing that the 10GBE card is also slower than on other 
systems ;-(

Stefan