Re: [perfmon2] deterministic event on 8-core Intel i7 processor

[stephane e. <er...@go...>]

On Thu, Mar 25, 2010 at 7:20 PM, Vince Weaver <vwe...@ee...> wrote:
> On Thu, 25 Mar 2010, stephane eranian wrote:
>
>> vince,
>>
>> Could you make your program such it has only 1 billion instructions?
>> I want to see if there is some correlation with counter overflows.
>> They are actually only 31 bit on Intel.
>
> sure, I've attached the 1 billion instruction version.
>
> I'm also working on a few memory microbenchmarks too to see if I can maybe
> find any patterns in the retired_stores cases.
>
I strongly believe this is related to interrupts. That's the only explanation
for the fluctuations. Furthermore, it's not the PMU interrupts,
because those, I assume,
are constant for this test program.