Tomas, On Mon, Apr 21, 2008 at 10:23 AM, Tomas Tuma1 <[EMAIL PROTECTED]> wrote: > > Vince, > > > > I'm not sure if it's causing this particular problem for you, but check > > the intel errata. There's one for this perf counter that makes the count > > vary with system frequency on some machines. A core2 machine we have > > exhibits this erratum. > > Thank you, it is important to know that. > > > > > > I don't think that would cause a 100x difference though. > > > > The output with sampling period set to 1000 ms (1s) looks like this > (the first event is the CPU_CLK_UNHLATED:REF, the second event are cache > misses - not important): > > CPU0 61904654 77838 > CPU1 32798577 47473 > # > CPU0 168643020 213794 > CPU1 90882904 171191 > # > CPU0 590366000 770770 > CPU1 1172523359 1644810 > > Fluctations are not unexpected when the system is doing nothing (or at least you think it is). What is more important is to verify that when you have a constant workload the count for REF remains fairly constant and close to peak for a nonblocking workload, i.e., a stupid noploop program such as (pfmon/tests/noploop).
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