[gecode-users] Gecode 3.5.0 faster than Gecode 3.7.0?

[Kish Shen]

Hi,

I have just upgrade the ECLiPSe interface to Gecode from Gecode 3.5.0 to 
3.7.0. As I am currently doing some work on improving the performance of 
the interface, I have been doing some timings with example programs, and 
to my surprise, one of the example is running consistently faster with 
3.5.0. The run-times are:

3.5.0:        16.34s
3.7.0:        19.99s

The only change between these two is the version of Gecode used (plus 
the changes in the C++ code needed for the upgrade, i.e. the #include 
for the graph and scheduling modules).

As the program is written in ECLiPSe, there is no direct record of the 
actual Gecode API calls made. The problem is the "roster" example from 
the ECLiPSe website, modified for use with the Gecode interface. This 
example is solving a simple rostering problem, and there are a lot of 
relational constraints posted, plus some boolean expressions, all posted 
via the MiniModel, and there are also some count contraints (occurrences 
of one value variant). The search is done in ECLiPSe, i.e. not using the 
search-engines of Gecode.

Is the above information sufficient for even guessing what the slow down 
might be due to? If not, what additional information might be needed?

Cheers,

Kish

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