"fastfib" in the gf package faster than "fib"

"It's not clear where we could actually get some useful results with
a reasonable amount of programming.  But of course if you have ideas,
dive in!"

It would be nice if operators and functions "thread" over lists.  Mathematica I think does this, at least they claim to without defining "thread over a list".  I think they mean one thread is created for each element in the list.  That would be a nice place to start with just a little programming and lots of gains.

"I don't know if there are good debugging tools for parallel Lisp code...."

Just use assertions, that is good enough generally, I rarely use debuggers personally but they are nice for some really nasty bugs.  The kind you get when you are inexperienced in a new language, well in that case debuggers don't help much anyway.

Rich


 ------------Original Message------------
From: "Stavros Macrakis" <macrakis at alum.mit.edu>
To: "Richard Hennessy" <rvh2007 at comcast.net>
Cc: "Maxima List" <maxima at math.utexas.edu>
Date: Tue, Jul-8-2008 6:10 PM
Subject: Re: [Maxima] "fastfib" in the gf package faster than "fib"

On Tue, Jul 8, 2008 at 3:59 PM, Richard Hennessy <rvh2007 at comcast.net> wrote:
> Any chance of Maxima or some Lisp implementations soon being able to use core duo correctly (e.g. multi-threading)?  My PC has 2 cores and Maxima never uses more than %50 of the available CPU time.  I have written screen savers that use %100 percent but who cares about that.  I don't use them.  Why fry my CPU?

It would certainly be nice to get an almost 2x speed improvement, but...

* I don't think any of our usual Lisps (GCL, CMUCL, CLISP, etc.)
support multiprocessor threads. The biggest challenge there is garbage
collection, though they probably have other global structures
internally that would pose difficulties.
* Common Lisp as far as I know has no standard interface to threads,
so that means portability would be a problem.
* Many parts of the system would probably not benefit at all.
* It's not clear where we could actually get some useful results with
a reasonable amount of programming.  But of course if you have ideas,
dive in!
* Much of Maxima's internals depend heavily on serialization, as they
use global variables etc.  Even if you want to parallelize at a high
level, you run into the problem of keeping things like the "assume"
database separate for different execution paths. Then again, some
kinds of calculations could take advantage of parallelization at the
process level, obviating the need for mucking around with Maxima
internals.
* I don't know if there are good debugging tools for parallel Lisp code....
* For nicely modular calculations which run for a long time, these can
be run in separate processes which can do whatever they like,
including cloud computing (run your calculation on a hundred virtual
machines at Amazon!).

In any case, I'm not quite sure what exactly your project is and how
we can help!  Presumably it's something more interesting than a screen
saver....

           -s