Memory – Part 4: Intersec’s custom allocators

Re:Memory – Part 4: Intersec’s custom allocators by blue11 on Tuesday October 01, 2013 @01:48PM (#6477783)

Sorry to nitpick, but I believe the time difference code has an error of 1 millisecond 25% of the time:

    int64_t delta = tv2->tv_sec - tv1->tv_sec;
    return delta * 1000 + (tv2->tv_usec - tv1->tv_usec) / 1000;

One way to fix it is:

    int64_t deltasec = tv2->tv_sec - tv1->tv_sec - 1;
    int64_t deltausec = tv2->tv_usec - tv1->tv_usec + 1000000;
    return deltasec * 1000 + deltausec / 1000;

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Re:Memory – Part 4: Intersec’s custom allocators by fruneau on Tuesday October 01, 2013 @03:11PM (#6478408)

The diff is a truncation. The actual error rate is 0.5ms on average. By using a round instead of truncation, we can reduce the error to 0.25ms on average.

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Re:Memory – Part 4: Intersec’s custom allocators by blue11 on Tuesday October 01, 2013 @03:40PM (#6478582)

Well, that much is obvious. But if you are going to truncate, you should be consistent. Always truncate towards 0, not sometimes towards 0 and sometimes towards infinity.

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