[Scip] Tweaking SCIP parameters for speed-up

[michael.winkler at zib.de]

Hi Sergey,

I also have some question besides Marcos.

You experienced a speed up factor of 2; on which test set or test
instances, are these instances similar in their structure?

We are sure that parameter for a particular instance type can be improved,
but how does your tuning works on an instances set like the MIPLIB?

Do you check the different results of the runs for feasibility/optimality
or compare the solution value for each instance?

Is Turbo Boost and Hyper-threading disabled for your results and are the
runs performed exclusively on a computer?

Best, Michael

> Hi Sergey,
>
> I would be interested not so much in the implementation, but in the
> methodological background.
>
> Firstly it estimates how long it takes to solve single problems with
>> default parameters.
>
>
> How would you do that, in particular for those runs that hit the time
> limit? I believe a LOT of people would be interested in such an estimate.
>
>
>
>> Then we do a single run (for every problem) for every special value
>> (e.g.
>> -1 or 0) of every parameter and two runs for ranged parameters (bigger
>> and
>> lower than default values). That is about 3000 runs for every problem in
>> a
>> test set so I use a cluster of virtual machines in a cloud for the
>> computations. After this step the tool compares the impact which
>> parameters
>> and their values make on the solving time.
>
>
> How? Considering a single parameter at a time? Or their combination? Or
> pairs? Or ...
>
>
>> Finally the tool takes four parameters (and their values) with the
>> biggest
>> impact and finds their best combination. This step is repeated for a fey
>> times
>
>
> "This step"? Why repeating the four-parameter-combinations? For taking
> into
> account performance variability?
>
>
>> and we get a settings file which speeds up computations noticeably for
>> the
>> given set of problems.
>
>
> Cool. Still would be interested in details.
>
>
> Take care
> Marco
>
>
>
>
> --
> Prof. Dr. Marco Lübbecke
> RWTH Aachen University
> Chair of Operations Research
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>
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>
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