Re: Xen 4.2.2 / KVM / VirtualBox benchmark on Haswell

[George Dunlap <George.Dunlap@eu.citrix.com>]

On Thu, Jul 11, 2013 at 11:53 AM, Dario Faggioli
<dario.faggioli@citrix.com> wrote:
> On mar, 2013-07-09 at 16:54 +0100, Gordan Bobic wrote:
>>  The process migration overheads are _expensive_
>>
> Indeed!
>
>>  - I found that on bare
>>  metal pining CPU/RAM intensive processes to cores made a ~20%
>>  difference to overall throughput on a C2Q class CPU (no shared caches
>>  between the two dies made it worse). I expect 4.3.x will be a
>>  substantial improvement with NUMA awareness improvements to the
>>  scheduler (looking forward to trying it this weekend).
>>
> Well, yes, something good could be expected, although the actual
> improvement will depend on the number of involved VMs, their sizes, the
> workload they're running, etc.
>
> When I tried to use kernel compile as a benchmark for the NUMA effects,
> it did not turn out that useful to me (and that's why I switched to
> SpecJBB), but perhaps it was me that was doing something wrong...

In my experience, kernel-build has excellent memory locality.  One
effect is that the effect of nested paging on TLB time is almostt nil;
I'm not surprised that the caches make the effect of NUMA almost nil
as well.

 -George