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Date: Sat, 02 Jul 2011 16:50:16 -0700
From: Patricia Shanahan <pats@acm.org>
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On 7/2/2011 3:45 PM, lbrt chx _ gemale kom wrote:
>
> I have searched to no avail for some kind of hardware baseline
> performance test for a piece of code.
>
> Notice that I don't mean to "profile" code, with "baseline" I mean
> that the actual performance of an algorithm should me gauged against
> its  underlying hardware and OS, like its I/O subsystem (RAM (types,
> speed, amount), file access, ...)
>
> We have all learned we should avoid String(s) and use StringBuffer(s)
> or better yet StringBuilder(s) but there is definitely more to
> performance testing/gains

Personally, I have not learned to avoid Strings. I use them where
appropriate, for example when I have an immutable string. I use
StringBuilder when I need to build a string through many steps.

In general, benchmarking, like any experiment, only makes sense if you
have some questions you want answered, and the measurements will answer
those questions. I'm not at all clear what your questions are.

"Performance of an algorithm" is a non-trivial concept. The most
algorithm-specific measure of performance is computational complexity,
but that is a matter of analysis, not measurement.

Of course, one often needs to know how fast an algorithm will run for a
specific problem size on a specific system. In that case, measurement is
definitely the way to go.

With modern computers, any sort of isolated measurement can be
misleading. There is so much caching and prediction that code can behave
very differently in different contexts.

Patricia