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    SubjectRe: Sched - graphic smoothness under load - cfs-v13 sd-0.48
    Bill Davidsen wrote:
    > Ray Lee wrote:
    >> On 5/19/07, Bill Davidsen <davidsen@tmr.com> wrote:
    >>> I generated a table of results from the latest glitch1 script, using an
    >>> HTML postprocessor I not *quite* ready to foist on the word. In any
    >>> case
    >>> it has some numbers for frames per second, fairness of the processor
    >>> time allocated to the compute bound processes which generate a lot of
    >>> other screen activity for X, and my subjective comments on how
    >>> smooth it
    >>> looked and felt.
    >>>
    >>> The chart is at http://www.tmr.com/~davidsen/sched_smooth_01.html for
    >>> your viewing pleasure.
    >>
    >> Is the S.D. columns (immediately after the average) standard
    >> deviation? If so, you may want to rename those 'stdev', as it's a
    >> little confusing to have S.D. stand for that and Staircase Deadline.
    >> Further, which standard deviation is it? (The standard deviation of
    >> the values (stdev), or the standard deviation of the mean (sdom)?)
    >>
    > What's intended is the stddev from the average, and perl bit me on
    > that one. If you spell a variable wrong the same way more than once it
    > doesn't flag it as a possible spelling error.
    >
    > Note on the math, even when coded as intended, the divide of the
    > squares of the errors is by N-1 not N. I found it both ways in online
    > doc, but I learned it decades ago as "N-1" so I used that.
    N-1 is for estimating the standard deviation from a random sample of a
    population (s), N is for calculating the standard deviation of a whole
    population (σ).

    xref http://en.wikipedia.org/wiki/Standard_deviation

    Yes, I am aware of the potential for Wikipedia articles to be wrong, but
    this article seems correct at first blush :)

    Matt


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