[Osi] How to speed-up flop-osi-cbc ?

[Matthew Saltzman]

On Tue, 2009-09-29 at 17:16 -0400, John J Forrest wrote:
> 
> Renato, 
> 
> I am not sure what -O2 switches on (or off).  If you go into Cbc (or
> other Coin projects) and just do configure and then look at Makefile,
> you will see that they tend to use -O3 and stuff like -ffast-math and
> -fomit-frame-pointer.  You may also want to use -march=native.  If
> NDEBUG is not defined in your Makefile that would also be a
> significant hit. 

For gcc, you can get a list of optimizations that are turned on at each
level with

        gcc -c -Q gcc -c -Q -On --help=optimizers

where -On is -O2, -O3, etc.

There are 162 binary optimization options that are controlled by these
options or can be controlled individually.  As John said, there are
other architecture options that can have an impact on performance.

I haven't tested with COIN code, but the Intel compilers are reported to
do much better on real Intel chips also.

> 
> I very much dislike OsiCbc but if that is what is being used then you
> may wish to instantiate it with a non-default CbcStrategy object.
>  This would allow you to have preprocessing which could help.  You can
> also customize that to use more/different cuts and heuristics. 
> 
> The message level for the OsiCbc object could also be modified before
> handing it to FlopC++. 
> 
> John Forrest 
> 
> 
> 
> [Osi] How to speed-up
> flop-osi-cbc ?
> 
> Renato
> Bruni 
> to: 
> osi 
> 09/29/2009 02:47 PM
> 
> Sent
> by: 
> osi-bounces at list.coin-or.org
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ______________________________________________________________________
> 
> 
> 
> 
> Hello everybody,
> 
> we are migrating from Cplex to FlpoC++/Osi/(Cbc or Glpk or Symphony).
> We are currently running some tests, but it seems that we need some
> advice
> to speed-up the open source solvers.
> 
> We are compiling all with gcc with option -O2 (optimization) but it
> does not
> seem much faster than the debug version. Which options would you
> recommend
> for speed? Also, we tried to disable messages from the solvers with
> the
> FlopC++ option "silent", but they write the same messages than before.
> Which
> other option we can try? Is there some other speed option (cut
> generation?)
> that maybe is disabled and one should enable? And how? Pointers to
> some
> documentation are appreciated.
> 
> Thanks a lot in advance.
> Best regards,
> Renato Bruni
> 
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-- 
                Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs