Have you considered checking hte return value of usleep (or sleep) to see how many actual seconds the method slept for, and then compare that with the delta from Time::HiRes::gettimeofday

I suspect that Time::HiRes::gettimeofday is in fact returning the accurate time for your system at the moment you call it, but you are seeing the larger then expected deltas because other things are happening on your system (besides the sleep) in between your calls -- Perl garbage collection, other processes on the same machine, etc....

My first suggestion was to try something like... 

 time perl -MTime::HiRes -le 'print ((Time::HiRes::gettimeofday())[1])
+ for (1..500)'

[download]

...where you sanity check the numbers printed out looking for any really odd jumps, and Compare the "real" time reported by your system with the delta between the first/last times printed so see if they concur.

But the compilation/interpreter startup is significant enough to provide missleading info at such a small level of granularity.

In reply to Re: Unexpected Timing spikes using Time::HiRes by hossman
in thread Unexpected Timing spikes using Time::HiRes by desemondo

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.