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Re: [Gcl-devel] gcl 2.7.0t5 and Maxima 5.9.1

From: Vadim V. Zhytnikov
Subject: Re: [Gcl-devel] gcl 2.7.0t5 and Maxima 5.9.1
Date: Sun, 28 Aug 2005 18:50:22 +0300
User-agent: Mozilla Thunderbird 1.0.6 (Windows/20050716)

Camm Maguire writes:
Greetings, and thanks Vadim for looking into this as always!

"Vadim V. Zhytnikov" <address@hidden> writes:


I did some little gcl 2.7.0t5 testing with
Maxima 5.9.1.  And I'm very impressed
by new twc memory consumption.  On all test
maximal memory footprint is almost the same as

On the other hand I observe some slowdown.
Performance degradation is not so significant
and even with it gcl is faster of as fast as CMUCL.
I have to stress that slowdown is not solely due to
smaller hole and more frequent relocatable pages GC.

Others have noticed some slowdown, at times approacing 15%.  My guess

I observe even bigger slowdown.  For example 31 vs 37 seconds
(net time without GBC). It's about 20%.

is that the compiler work I've been doing has silently eliminated some
earlier optimizations, inadvertently of course, but in fact the
compiler now knows a lot more about types, and if everything doesn't
match, then the code produced can be less optimial at the moment.  It
would be most helpful if you could break this down using the gprof
facility or otherwise.  Build atop a gcl build with --enable-gprof in
t5 and 2.6.6 -- all will be somewhat slower due to the profiling
overhead, but the rations should be the same.  THen sandwich your test
between (si::gprof-start) and (si::gprof-quit).  Then please prune it
down to the extent possible and post your results.  If you see a
particularly poorly compiled routine, please post the disassembly in
t5 and 2.6.6 (i.e. (disassemble 'foo)).  This sort of feedback is
really essential to make sure we don't give up performance as we move
toward compilance.

I'll do this as soon as time permits ...

 >>I also observe some small problems:

1. It seems that set-hole-size doesn't work with
gcl 2.7.0t5 - to be more precise it has no effect on
GBC process.

2. I see wrong GBC messages - lot's of GBC messages
for STRUCTURE while in reality this is probably
4w strauctures CFUN GBC.

Could you send me a small test so I can reproduce here locally?

Test and it's output is in the attachment.
See STRUCTURE and CFUN in (room) and GBC messages.
I also tried various (si::set-hole-size NNN) in
maxima-init.lisp - no effect whatever.

     Vadim V. Zhytnikov


Attachment: test.out.gz
Description: GNU Zip compressed data

:lisp (room)
:lisp (setq si::*notify-gbc* t)
:lisp (si::gbc-time 0)
:lisp (room)
:lisp (format t "~%GBC time ~4,2f seconds" (/ (si::gbc-time) 100.))

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