MinGW and Python

[Alex Martelli]

Edward Elliott <nobody at 127.0.0.1> wrote:

> Alex Martelli wrote:
> > about MacOSX, which also uses gcc: 14% faster pybench using Python 2.4.3
> 
> this is the second time I've seen that 14% figure.  OOC, where does it come
> from?  the data sets you posted show an average 12.6% speedup.  14 is an
> odd way to round. :)

I believe 12.6% is the result if you pick the faster speed as a
denominator (and so it's the right figure for a _slowdown_,
hypothetically moving from fast to slow case), 14% if you pick the
slower speed as a denominator (i.e., for a _speedup_).

Of course if you work with times rather than speeds it's the other way
around.


> I don't think it's very useful to talk about average speedups from a
> benchmark of equally-weighted feature tests.  the data shows wildly varying
> differences in performance for each test.  a real-world application could
> be much slower or much faster on either platform depending on its feature
> mix.  not the type of thing that's amenable to expression as a single
> value.

I believe the single figure is a useful summary.  Even the most
sophisticated benchmarks are eventually boiled down to single figures,
as in "so many SPECmarks" etc, because in everyday discourse a scalar is
what you can reasonably discuss.  Sure, philosophically speaking it
makes no sense to say that a compiler is better or worse than another at
optimization, without adding a lawyer's brief worth of qualifications
each and every time.  In real life, it's a useful and practical
temporary simplification, and engineers (as opposed to mathematicians
and philosophers) have a bias towards practical usefulness.


Alex