Frederic Dambreville a écrit :

...

Generally, no. It's also hard to do in a general Array, since each Float is a full object, any arithmetic on it does unboxing and boxing

OK! The way I use it, this implies a strong limitation of squeak; each algorithm with intensive mathematical computation will need a dedicated primitive...

...

of a newly allocated Float object. To speed this up considerably you would have to create primitive array that do not hold objects but.

?'but'?

So, I understand that I need:

• intermediate classes, for storing 'true' arrays,
• translators for converting to/from standard squeak classes from/to

these intermediate classes,

• primitives for array computation on these classes

or something like that.

A lot of work... Are there people, which have already done a part of the job? Or are interested by such classes and primitives?

Thanks,

FD

When you think of it, it's pretty well the case of Matlab:

Matlab interpreter is very inefficient. (Don't you write a loop in matlab !). And each arithmetic computation a = b*c; allocates a mxArray... like Smalltalk will allocate a Float...

However, Matlab has much of the needed array primitives. Given that, the idea is to implement such array primitives in Smalltalk too. I started to interface Blas and Lapack to Smalltalk, this is called Smallapack (search with google).

Though i have a decently working version under Visualworks and Dolphin, the Squeak one is unfortunately bleding edge (that means the tests do not pass, worse, they can crash or block your image).

By now, i'm not working on it. But if you want to use it as a starting point, i can provide some help.

Cheers.

Nicolas

So, I understand that I need:

• intermediate classes, for storing 'true' arrays,
• translators for converting to/from standard squeak classes from/to

these intermediate classes,

• primitives for array computation on these classes

or something like that.

The KedamaPlugin2 has some more operations defined, including the mixed FloatArray and WordArray operations, and operations with mask-bits.

The following is probably a squeak-dev topic, but one thing that is conceivable is to have a primitive that takes a function name as string ('cos', 'sin', etc.) and in the primitive, it looks up the symbol in various library can call it:

----------------- primApply: aString toArray: aFloatArray into: resultArray

self var: 'val' type 'double'. func := dlsym(aString). 0 to: aFloatArray size -1 do: [:i| val := aFloatArray at: i. resultArray at: i put: (self cCode: '(*func)(val)'). ].

-----------------

-- Yoshiki

It is interesting to look at the Computer Language Benchmarks Game and see the relative speed of dynamic vs statically typed languages on micro-benchmarks (these are math heavy tests). I didn't look at the Lisp derivatives to see if they were using dynamic or static typing (I believe they can use either as required), but it looks like the fastest purely dynamically typed language I've used is Python with Psyco. That is about 7x slower than the fastest C++ implementation. The fastest smalltalk in the game is VisualWorks at about 10x slower than C++ and Squeak is about 50x slower than C++.

http://shootout.alioth.debian.org/gp4/benchmark.php?test=all&lang=all

I understand in theory it is possible to have good performance out of dynamicly typed languages, but it seems the only way to get good performance today is to punt out of your dynamic language into a C or Fortran library for all the heavy lifting. It's a shame really. In fact, I think there is a high-speed compiler for Smalltalk that is typeless, but it was swallowed by Sun before it took off.

David

On Thu, Jul 10, 2008 at 4:27 PM, Frederic Dambreville squeak@fredericdambreville.com wrote:

...

When you think of it, it's pretty well the case of Matlab:

That's it. Actually, I was also thinking about something like the J language.

...

Though i have a decently working version under Visualworks and Dolphin, the Squeak one is unfortunately bleding edge (that means the tests do not pass, worse, they can crash or block your image).

By now, i'm not working on it. But if you want to use it as a starting point, i can provide some help.

I will look at it. However, my contribution in the close future will be restricted to my current need (a Bellman-like equation propagation).

See you,

FD

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