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Performance Questions

Posted: Mon Apr 20, 2009 5:58 pm
by alston
Hi,

I had some basic questions about Opensim that relates directly to performance. Currently I'm getting my model running, and I was wondering about the computer limitations that I will have to work with. Along those lines there are three basic questions that I have.

My first question is about operating systems. My understanding of Opensim is that it runs on a Windows operating system. Which is fine by me, cause that is about all I know how to use. However, I know Windows eats up a lot of resources just to get running. Has there, or is there going to be an effort to get Opensim to run on with Linux, or something like that?

My second question is how well does Opensim run on multiple processors?

My third question is can anyone give me some guidelines about how large, or how complicated, a model I can have and still expect the thing to run with two or three gig's of ram?

The reason I ask this is that I want to run a CMC analysis over about a half a second with about 60 DOF and about 150 to 200 actuators. I have access to a high powered computing system. The problem is that the system is Linux based, and most of the computing speed comes from parallel processing. I was hoping someone could give me some guidance about this sort of stuff. If Opensim is not going to work on a Linux system, I'm pretty sure I'm going to need to simplify my model. But if I need to simmplify my model, I was hoping someone could give me some guidelines about how much I need to simplify.

If anyone can give me some help about the OS, parallel processors, and the like, I would greatly appreciate it.
Thank you,
Joseph Alston

RE: Performance Questions

Posted: Mon Apr 20, 2009 6:18 pm
by samner
Hi Joseph,

Currently I am creating simulations of running using CMC with models that have 38 degrees-of-freedom and 92 actuators. I am using a PC with an Intel Pentium 4 chip with 3 GB of RAM. For a full gait cycle (about 0.8 seconds) CMC analysis takes about 10 minutes.

As for the status of OpenSim in Linux, I believe it could be built on Linux, but we don't currently support it. However the underlying dynamics engine (Simbody) and other core software can be installed and run on Linux (https://simtk.org/project/xml/downloads.xml?group_id=97)

I do not think anything has been done to take advantage of using multiple processors in OpenSim (some may be able to correct me), but it sounds like for the size of your problem, implementing this would not be worth the gains (unless you plan on running many, many iterations of your simulation).

Hope this helps,
Sam