[Coin-discuss] clp performance much worse with g++4.1 vs. g++4.0

[Ted Ralphs]

Each of the three projects you mentioned includes Clp 1.6.0 as part of 
its distribution, so all three of them are building an executable called 
"clp" from the Clp 1.6.0 source code and installing that executable in 
the same directory (the one you specified), each one overwriting the 
last. You can tell specifically what other releases a given project 
release depends on by looking at the subversion externals of the project 
in the source browser on the project's Trac page. For instance, in the 
case of Cbc, check out the very bottom of this page:

https://projects.coin-or.org/Cbc/browser/releases/2.0.0

So the "clp" you are ending up with is the Clp executable built as part 
of the Cbc distribution. Although all the executables use the same 
source code in this case, it is possible that the build is configured 
differently in each case because the presence or absence of other 
projects can trigger automatic changes in the configuration options. It 
seems to be the case that, in fact,  the executables built in each case 
are slightly different (I just checked this). I'm sure John can tell you 
exactly what the differences are.

Cheers,

Ted

Stuart A Siegel wrote:
> 
> After John mentioned that he doesn't see a difference I dug a bit 
> deeper.  It turns out that the compiler issue is a red herring, my 
> aplogies.  What's causing the performance difference is my (apparently) 
> incorrect build procedure.
> 
> When I build just Clp (using ../Clp-1.6.0 prefix=[somedirectory] && make 
> install) then performance is good from somedirectory/bin/clp
> 
> If I build Clp, Osi-0.97.0, and then Cbc-2.0.0 in that order using the 
> **same** prefix then somedirectory/bin/clp performs three times worse 
> than when I only build Clp.  This result is independent of the g++ 
> version being used.  I chose to build this way (all three into the same 
> install directory) because I had assumed that each provides a unique set 
> of shared objects, but my experience suggests that  this is not the case.  
> 
> John, I'll be at Watson tomorrow (in fact, I think I'm across the hall 
> from you) so I can show you what I mean.  I will post the mps file on my 
> gsa account and send you a link in separate message.
> 
> -----------------------------------------------------------------------------------------
> Stuart Siegel - IBM TJ Watson Laboratory 33-238
> (M) 914.396.9506 (H) 973.379.1810 (O) 914.945.1674
> 
> 
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-- 
Dr. Ted Ralphs
Associate Professor
Industrial and Systems Engineering
Lehigh University
(610)758-4784
ted at lehigh dot edu
www.lehigh.edu/~tkr2