[gambit-list] Experience with the new compile options
Marc Feeley
feeley at iro.umontreal.ca
Tue Aug 7 13:42:58 EDT 2007
On 7-Aug-07, at 11:31 AM, Bradley Lucier wrote:
> Marc:
>
> I've had a lot of experience now with the new compile options (and
> I'm not talking about --enable-gcc-opts) and I have to say that
> they just aren't worth it. You don't know which of them help the
> most in execution time, and you don't know which cost the most in
> compile time. (Hell, you don't even know which ones help *at all*;
> you could be running compiler passes that hurt run-time performance
> while eating up compile time.)
That's true.
>
> You ran a genetic algorithm to guess which optimizations to run.
> That's fine to get an idea of what to try, but it's not sufficient
> to foist this pain on your users. Even on my Opteron server
> development is painful.
I feel the same pain on my MacBook Pro.
>
> So pull back to the old
>
> -O1 -fno-math-errno -fschedule-insns2 -fno-trapping-math -fno-
> strict-aliasing -fwrapv -fomit-frame-pointer
Done.
>
> by default; even offer a configure optimization to add -
> D___OPTIMIZE_SPACE to the compile line. You have a development
> model that does whole-program compilation by default; it just can't
> support the default compiler options chosen at configure time.
Done. The configure option is "--enable-optimize-space".
On my 2GB 2GHz MacBook Pro using i686-apple-darwin8-gcc-4.0.1 I now
get these times (for a build with "make -j 2", and for running "gsi
tests/mix.scm") when using these configure options:
build gsi tests/mix.scm
EOS 60s 8.41s
<no options> 74s 8.52s
ESH EOS 123s 4.38s
ESH 147s 4.60s
ESH EGO EOS 222s 4.19s
ESH EGO 771s 4.33s
ESH = --enable-single-host
EOS = --enable-optimize-space
EGO = --enable-gcc-opts
It seems like using --enable-optimize-space gives a faster build
*and* faster execution. So maybe I will probably make this the
default if I observe the same thing on other benchmarks.
Marc
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