[plt-scheme] Re: Using PLT Scheme libs elsewhere?

On Mon, 21 May 2007, Danny Yoo wrote:

> > Previously, using mzscheme 360, and the scheme implementation of the md5
> > library, the time was almost 6 min.
> >
> > real	5m46.574s
> > user	1m21.794s
> > sys	0m4.231s
>
>
> I didn't want to guess on this one.  I applied the PLT profiler on this
> program (and including an inlined copy of the md5 library so the profiler
> could look through it.)
>
> The dominating factor here is the 32-bit word arithmetic within the loop
> in step4 of the md5 algorithm.  A good third or so of the total runtime
> appears to be spent doing "word+=!", one of the private functions in the
> module that simulates a 32-bit word arithmetic operation.
...
> You've highlighted that the performance might need to be tuned up a bit,
> so maybe someone can take a look to see if it's possible to make the word
> arithmetic faster.

The fixnum primitives should be fast, but they only work on 31-bit nums
(on 32-bit archs).
So this might be from words being bignums.

-- vyzo