Review of Andrei's std.benchmark

[Nick Sabalausky]

On Tue, 18 Sep 2012 18:02:10 -0400
Andrei Alexandrescu <SeeWebsiteForEmail at erdani.org> wrote:

> On 9/18/12 5:07 PM, "Øivind" wrote:
> > * For all tests, the best run is selected, but would it not be
> > reasonable in some cases to get the average value? Maybe excluding
> > the runs that are more than a couple std. deviations away from the
> > mean value..
> 
> After extensive tests with a variety of aggregate functions, I can
> say firmly that taking the minimum time is by far the best when it
> comes to assessing the speed of a function.
> 

*Ahem*: http://zedshaw.com/essays/programmer_stats.html

Your claim that the minimum time is sufficient is...ummm...extremely
unorthodox, to say the least. As such, you're going to need a far more
convincing argument than "It worked well for me."

I assume I don't need to preach that "Extraordinary claims require
extraordinary evidence". But, condensing benchmarks and statistics down
to "take the minimum" and saying that's sufficient is one heck of an
extraordinary claim. If you feel that you can provide sufficiently
extraordinary justification, then please do.

Otherwise, I think we'll need richer results. At the very least there
should be an easy way to get at the raw results programmatically
so we can run whatever stats/plots/visualizations/output-formats we
want. I didn't see anything like that browsing through the docs, but
it's possible I may have missed it.

That brings up another question too: I like the idea of a
one-stop-benchmarking-shop, much like we have for unittests, but maybe
reporting shouldn't be so tightly integrated and left more open for
integration with a proper statistics lib and more generalized
output abilities? But of course, that doesn't preclude having a nice
built-in, but optional, default report. (Again though, maybe I'm
overlooking something already in the module?)

One other nitpick: My initial impression is that the
"benchmark_relative_file read" stuff seems a bit kludgey (and
confusing to visually parse). Is there maybe a better way to handle
that? For example, inspired by getopt:

printBenchmarks!(
    "file write", { std.file.write("/tmp/deleteme", "hello, world!"); },
    BenchmarkOption.relative,
    "file read", { std.file.read("/tmp/deleteme"); },
    "array creation", { new char[32]; })
    ();