[armedbear-devel] (lisp) Stack management efficiency

Erik Huelsmann ehuels at gmail.com
Tue Jul 21 10:07:23 UTC 2009

Peter Graves pointed me at the language/implementation efficiency
shootout at http://www.ffconsultancy.com/languages/ray_tracer/benchmark.html
which implements a ray tracer in a multitude of languagues, one of
them being Common Lisp.

There are a number of rows, which I conviniently name version 1 (row
1) to version 5 (last row). Peter points out that version 1 isn't
optized at all: all functions lead to function calls (no inlining).

When running this code, it takes around 1440 seconds on my PC. Then I
modified the stack management routine to re-use available stack frames
(and conses), instead of creating new ones on every call. This took
execution time down to around 1240 seconds. A good improvement, I'd

However, with the change described above, stack frames won't ever
become garbage anymore. My question is: does the loss of GC-ability
outweigh the performance gain?

Please note that it's possible to run without a lisp stack (but that
also means without traces) by compiling code with a (SPEED 3)




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