[Openmcl-devel] impact of number of arguments and closures on performance

[Taoufik Dachraoui]

how FriCAS does perform compared to CCL, for example, can you test for me
the fibonacci function

on my computer ccl takes 7.22seconds, what about FriCAS on CCL?

ie. (defun fib (n) (if (< n 2) n (+ (fib (- n 1)) (fib (- n 2)))))
? (time (fib 45))
(FIB 45)
took 7,225,458 microseconds (7.225458 seconds) to run.
During that period, and with 16 available CPU cores,
     7,222,601 microseconds (7.222601 seconds) were spent in user mode
         2,253 microseconds (0.002253 seconds) were spent in system mode
1134903170

I am interested to know how fast can be an interpreter compared to the host
language (few hundreds times slower or at best 10 times slower?)
is there any benchmark tests of interpreters compared to their host
languages?

Thanks

-taoufik


On Tue, May 12, 2020 at 2:46 PM Waldek Hebisch <hebisch at math.uni.wroc.pl>
wrote:

> On Tue, May 12, 2020 at 08:54:03AM +0200, Taoufik Dachraoui wrote:
> > I am implementing a new lisp dialect programming language (statically
> > typed, generic programming, lambda calculus + syntax)
> > I found that limiting the number of variables in a closure may be of help
> > in optimising the interpreter (simulator)
> >
> > I would like to know how closures are efficiently implemented in lisp
> > languages
> >
> > In the implementation I have a notion of frame which contains the address
> > of a function and the variables in a closure
> >
> > and I am trying to optimise the implementation by limiting the size of
> the
> > closure but this may not be acceptable
> >
> > Any thoughts are welcome, and wanted to know how Clozure CL is
> implemented
> > and if there is a notion of frames
>
> I do not know how Clozure CL implements closures, but I can tell
> you about two different system.  One is FriCAS which contains
> staticaly typed language compiling to Common Lisp (you can run
> FriCAS on top of Clozure CL).  In FriCAS finction is represented
> by Lisp dotted pair, CAR is Lisp function while CDR is extra
> argument.  For closures the extra argument is Lisp vector
> containing captured values.  Currently FriCAS has no limit
> on number of captured, while number of arguments to functions
> is limited to about 30.  Limit on number of arguments is
> kind of soft: FriCAS need a few Lisp symbols for each argument.
> If needed one can increase number of arguments by adding
> extra sysmbols (but up to now current limits are adequate).
>
> Concerning efficiency, FriCAS compiler in several places
> uses linear searches and large number of relevant objects
> slows down compilation.  My experiments suggest that
> Clozure CL has similar problem, normaly Clozure CL
> compiler is quite fast, but with large number of variables
> it considerably slowed down (at least that happended in the
> past using earlier version).  Still, slowing down
> compilation seems to be mcuh better than hard coded
> limit.
>
> Another system is Poplog.  It offers Lispy data structures
> and user defined syntax (there is user accessible interface
> to code generator, so users can generate arbitrary code
> from new sysntax).  In Poplog closures are implemented
> in two step way.  Namely, Poplog allows "partial
> evaluation", that is you can replace last k arguments
> to function by fixed values.  "partial evaluation" via
> small stub which has table of fixed values and copies
> values from table to argument positions.  Actual code of
> function takes extra arguments for each closed over
> variable.
>
> --
>                               Waldek Hebisch
>


-- 
Taoufik Dachraoui
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