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    SubjectRe: [RFC][PATCH 0/6] perf: x86 RDPMC and RDTSC support
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    On Wed, 2011-12-21 at 16:32 -0500, Vince Weaver wrote:

    > * One, is it possible to detect at runtime that rdpmc() is supported?
    > Maybe a field in the mmap'd buffer that can be read?

    Ingo suggested a similar thing, will implement (although Christmas might
    interfere with delivery timelines etc..).

    > * Second, if I try a start / run 100M instructions / read
    > and measure retired instructions I get:
    > 281474977711543 instructions
    > This is 0x10000000f45b7 which is 1<<48 + 100M. I guess an artifact
    > of how the counters are set up? Is it possible to have this start
    > at 0?

    Its supposed to be 0 based, clearly I messed up something and need to go
    figure out what. Thanks for reporting.


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