[cairo] Does the performance suite work?

Soeren Sandmann sandmann at daimi.au.dk
Mon Oct 15 12:37:53 PDT 2007

"BJörn Lindqvist" <bjourne at gmail.com> writes:

> It seems like the cairo-perf program doesn't work at all. The variance
> in the results I get are so big that it can't be used to measure
> performance adequately.

I don't know if it explains the variance you see, but I definitely
think there is a problem with the cairo performance test suite. Quote
from http://lists.freedesktop.org/archives/cairo/2007-June/010813.html :

        The cairo-perf program essentially does this:

                for (i = 0; i < n_iters; ++i)
                        timings[i] = run_test();

                        compute_stats (i);

        where compute_stats() involve sorting the timings array. This
        means not only that the test suite is horribly slow with many
        iterations, but also that the numbers will be unreliable due
        to the cache effects of sorting a huge array between
        iterations. So the numbers above are all done with the
        compute_stats() call moved out of the loop[1]

        [1] The patch is here: 


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