I noticed that when I run the solver via the GAMS IDE or Python API I don't use more than ~33% of my RAM. Is there an artificial barrier which I can put up or disable?
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2$\begingroup$ Why the driveby downvote? $\endgroup$– Mark L. StoneCommented Dec 13, 2020 at 19:34
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$\begingroup$ Which solver are you using? $\endgroup$– Kevin DalmeijerCommented Dec 14, 2020 at 3:09
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2$\begingroup$ Not sure about the reason you want the model to use more memory, but -- of course -- small models use less memory than big ones. CPU percentage can be increased by using more threads (default in GAMS is 1 thread). BTW that will also increase memory usage. $\endgroup$– Erwin KalvelagenCommented Dec 14, 2020 at 7:42
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$\begingroup$ @KevinDalmeijer IBM ILOG CPLEX 32.2.0 rc62c018 Released Aug 26, 2020 WEI x86 64bit/MS Window --- GAMS/Cplex Link licensed for continuous and discrete problems. Cplex 12.10.0.0 $\endgroup$– EddieeCommented Dec 14, 2020 at 12:06
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$\begingroup$ @ErwinKalvelagen Thank you. I let it be like that since i am only making a comparison and not striving for maximum speed? $\endgroup$– EddieeCommented Dec 14, 2020 at 12:07
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2 Answers
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As @ErwinKalvelagen pointed out: by default gams cplex uses only 1 thread which results in a low usage of the pc ressources.
In order to change this one has to increase the thread number so that multiple cores can be used at the same time: https://support.gams.com/solver:multiple_cplex_threads
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This analogy might help: CPU usage is like the power output of an engine - more is better in terms of performance. Memory usage is more like the heat produced by the engine - too much heat, aka memory capacity exceeded, and the engine breaks down.
There is simply no reason in trying to increase or even max out memory usage.
