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    SubjectRe: [RFT] Please test rdtsc on various x86-64 hardware (app included)
    Date
    On 18/04/11 20:32, Andrew Lutomirski wrote:
    > Hi all-
    >
    > I'd appreciate some help testing rdtsc's ordering wrt memory on
    > various hardware. You can download evil-clock-test code at:
    >
    > https://gitorious.org/linux-test-utils/linux-clock-tests/blobs/raw/master/evil-clock-test.cc

    A low power core2 server:

    CPU vendor : GenuineIntel
    CPU model : Intel(R) Core(TM)2 Duo CPU T8100 @ 2.10GHz
    CPU stepping : 6
    TSC flags : tsc constant_tsc
    Using lfence_rdtsc because you have an Intel CPU
    Will test the "lfence;rdtsc" clock.
    Now test passed : margin 84 with 39213496 samples
    Load3 test passed: margin 20947164 with 15 samples
    Load test passed : margin 52 with 12466437 samples
    Store test failed as expected: worst error 1397 with 11151528 samples

    That margin number seemed a bit high, rerunning gives:

    CPU vendor : GenuineIntel
    CPU model : Intel(R) Core(TM)2 Duo CPU T8100 @ 2.10GHz
    CPU stepping : 6
    TSC flags : tsc constant_tsc
    Using lfence_rdtsc because you have an Intel CPU
    Will test the "lfence;rdtsc" clock.
    Now test passed : margin 84 with 39201440 samples
    Load3 test passed: margin 7991 with 15 samples
    Load test passed : margin 52 with 12482714 samples
    Store test failed as expected: worst error 2457 with 11129294 samples

    Frank



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