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    SubjectRe: [PATCH] x86: Run checksumming in parallel accross multiple alu's

    * Neil Horman <nhorman@tuxdriver.com> wrote:

    > Prefetch and simluated adcx/adox from above:
    > Performance counter stats for './test.sh' (20 runs):
    >
    > 35,704,331 L1-dcache-load-misses ( +- 0.07% ) [75.00%]
    > 0 L1-dcache-prefetches [75.00%]
    > 19,751,409,264 cycles # 0.000 GHz ( +- 0.59% ) [75.00%]
    > 34,850,056 branch-misses ( +- 1.29% ) [75.00%]
    >
    > 7.768602160 seconds time elapsed ( +- 1.38% )

    btw., you might also want to try measuring only the basics:

    -e cycles -e instructions -e branches -e branch-misses

    that should give you 100% in the last column and should also allow
    you to double check whether all the PMU counts are correct: is it
    the expected number of instructions, expected number of branches,
    expected number of branch-misses, etc.

    Then you can remove branch stats and add just L1-dcache stats - and
    still be 100% covered:

    -e cycles -e instructions -e L1-dcache-loads -e L1-dcache-load-misses

    etc.

    Just so that you can trust what the PMU tells you. Prefetch counts
    are sometimes off, they might include speculative activities, etc.

    Thanks,

    Ingo


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