[Gcl-devel] Floating-point performance of GCL? Bug?

[Nicolas Neuss]

Hello,

I am checking if it is a reasonable alternative to use my PDE-solver
Femlisp (www.femlisp.org) with GCL.  Femlisp relies heavily on having good
floating point performance.  Therefore I tried first the test program

http://www.iwr.uni-heidelberg.de/~Nicolas.Neuss/misc/mflop.lisp

which gives an error with GCL from Debian:

----------------------------------------------------------------
address@hidden:~$ gcl
GCL (GNU Common Lisp)  2.6.2 CLtL1   Jun 29 2004 18:53:13
Source License: LGPL(gcl,gmp), GPL(unexec,bfd)
Binary License:  GPL due to GPL'ed components: (READLINE BFD UNEXEC)
Modifications of this banner must retain notice of a compatible license
Dedicated to the memory of W. Schelter

Use (help) to get some basic information on how to use GCL.

>(compile-file "mflop.lisp")

Compiling mflop.lisp.
Warning: The OPTIMIZE quality DEBUG is unknown.
Warning: The OPTIMIZE quality DEBUG is unknown.
End of Pass 1.  
End of Pass 2.  
OPTIMIZE levels: Safety=0 (No runtime error checking), Space=0, Speed=3
Finished compiling mflop.lisp.
#p"mflop.o"

>(load *)

Loading mflop.o
DDOT-long: 241.02 MFLOPS

Error: Value stack overflow.
Fast links are on: do (si::use-fast-links nil) for debugging
Error signalled by LOAD.
Broken at MFLOP-TEST.  Type :H for Help.
>>
----------------------------------------------------------------

while the result for CMUCL is:

-----------------------------------------------------------------
* (load *)

; Loading #p"/home/neuss/mflop.x86f".
DDOT-long: 271.83 MFLOPS
DDOT-short: 712.27 MFLOPS
DAXPY-long: 152.74 MFLOPS
DAXPY-short: 484.76 MFLOPS
T
*
----------------------------------------------------------------

Now, the 241 MFLOPS looks promising.  But why the error?  Furthermore, also
DAXPY-LONG works, but yields a disappointing performance.

Yours, Nicolas.