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

[Christian Schulte]

This is most likely due to the count constraint. In Gecode 3.7.0 it tries to
do more pruning and that might cause the slow down (and your examples might
not necessarily profit from the additional pruning).

Cheers
Christian

--
Christian Schulte, KTH, web.it.kth.se/~cschulte/

-----Original Message-----
From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
Of Kish Shen
Sent: Tuesday, September 13, 2011 6:41 PM
To: users at gecode.org
Subject: [gecode-users] Gecode 3.5.0 faster than Gecode 3.7.0?

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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