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Parameteric vs. Batch vs. Cluster sweeps

Posted Aug 13, 2014, 1:03 a.m. EDT Cluster & Cloud Computing, Parameters, Variables, & Functions, Studies & Solvers Version 4.4 4 Replies

Amr Al Abed
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Hi,

I have a time-dependent model and I would like to sweep through a range of values of one of the model parameters. The problem is an 'embarrisingly parrallel problem' and very much similar to the example given in this COMSOL blog post:

www.comsol.com/blogs/added-value-task-parallelism-batch-sweeps/

However after much reading on the support pages and in the reference manual, I am still not quite sure how COMSOL handles the various sweep study options:
1. Parametric Sweep
2. Batch Sweep
3. Cluster Sweep

I'm a bit confused because I have managed to use the Batch Sweep to solve the model on our computational cluster. So then how is a Cluster sweep different to a Batch sweep? When is it advantageous to use over the other?

Regards
Amr

4 Replies Last Post May 18, 2017, 6:31 p.m. EDT
COMSOL Moderator

Hello Amr Al Abed

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Alexey Trukhin
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Posted: 9 years ago Sep 12, 2015, 1:05 p.m. EDT
I have the same question regarding all the variants for `sweeps`. Does anybody know the difference between them?
I have the same question regarding all the variants for `sweeps`. Does anybody know the difference between them?
Ying Tang
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Posted: 8 years ago May 18, 2017, 6:45 a.m. EDT
I am also puzzled by this question. anyone knows the difference?
I am also puzzled by this question. anyone knows the difference?
Walter Frei COMSOL Employee

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Posted: 8 years ago May 18, 2017, 2:08 p.m. EDT
Hello,

A parametric sweep is performed within the COMSOL Multiphysics GUI, so you have to have the software up and running.

A batch sweep is the same as a parametric sweep, but you simply run the software from the command line, without the GUI. Functionally, is is equivalent to the parametric sweep, it will take the same time to do a batch sweep as a parametric sweep. For details on this, please see:
www.comsol.com/blogs/how-to-run-simulations-in-batch-mode-from-the-command-line/
You can also launch a batch sweep from within the GUI itself, and keep working within the GUI. For details on this, please see: www.comsol.com/blogs/the-power-of-the-batch-sweep/

A cluster sweep is only available if you're using a Floating Network License type (www.comsol.com/products/licensing) and lets you solve on a cluster. That is, different nodes of the cluster will be solving different parameters, in parallel. So, a parametric sweep (or batch sweep) run on a single computer would solve all of the different sweep values sequentially (say 1000 different parameters, one after another.) A cluster sweep could distribute those 1000 different parameters onto, e.g. 100 different nodes, solving only 10 parameters on each cluster node, in parallel. This would cut total runtime by ~100-fold.

Hello, A parametric sweep is performed within the COMSOL Multiphysics GUI, so you have to have the software up and running. A batch sweep is the same as a parametric sweep, but you simply run the software from the command line, without the GUI. Functionally, is is equivalent to the parametric sweep, it will take the same time to do a batch sweep as a parametric sweep. For details on this, please see: https://www.comsol.com/blogs/how-to-run-simulations-in-batch-mode-from-the-command-line/ You can also launch a batch sweep from within the GUI itself, and keep working within the GUI. For details on this, please see: https://www.comsol.com/blogs/the-power-of-the-batch-sweep/ A cluster sweep is only available if you're using a Floating Network License type (https://www.comsol.com/products/licensing) and lets you solve on a cluster. That is, different nodes of the cluster will be solving different parameters, in parallel. So, a parametric sweep (or batch sweep) run on a single computer would solve all of the different sweep values sequentially (say 1000 different parameters, one after another.) A cluster sweep could distribute those 1000 different parameters onto, e.g. 100 different nodes, solving only 10 parameters on each cluster node, in parallel. This would cut total runtime by ~100-fold.
Edgar J. Kaiser Certified Consultant
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Posted: 8 years ago May 18, 2017, 6:31 p.m. EDT

Functionally, is is equivalent to the parametric sweep, it will take the same time to do a batch sweep as a parametric sweep.


Walter is that correct? Shouldn't a small model run faster in a batch sweep? E.g. we have four parameter values, we allow 4 parallel processes on a 4 core machine and allow 1 core per process?

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
[QUOTE] Functionally, is is equivalent to the parametric sweep, it will take the same time to do a batch sweep as a parametric sweep. [/QUOTE] Walter is that correct? Shouldn't a small model run faster in a batch sweep? E.g. we have four parameter values, we allow 4 parallel processes on a 4 core machine and allow 1 core per process? Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com

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