Messages in this thread | | | Date | Tue, 23 Jun 2009 15:59:59 +0800 | From | Yong Wang <> | Subject | Re: perf_counter Atom patch |
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On Tue, Jun 23, 2009 at 09:45:03AM +0200, stephane eranian wrote: > > Unfortunately, I don't have a N270 to compare with your results. > We need to verify whether or not N270 implements the fixed counters. > Does it report architected perfmon v3 or v1? >
All Atom processors report perfmon v3 as specified in SDM. N270 is no exception.
> > The return value of CPUID(0xa) is indeed bogus, too and there is another quirk for that in > > intel_pmu_init() in arch/x86/kernel/cpu/perf_counter.c > > > > x86_pmu.num_counters_fixed ?? ?? ??= max((int)edx.split.num_counters_fixed, 3); > > > > Is this what you were talking about? > > Not quite, because with the max() you'd have a problem on Intel Core > Duo/Solo processors > as they do implement the first generation of architected perfmon and > that one did not have > fixed counters. So you'd have to special case family=6 model=14.
That has been taken into account actually. Only perfmon v2 and above are supported as you see in intel_pmu_init().
if (version < 2) return -ENODEV;
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