Learning Forum

[javat33489]

Hello everyone. I work on a 24/48 core PC with an AMD EPYC core.
When I do a calculation without using DMP specifying the number of cores, the solution to the problem on 16 cores is faster than on 20 or 24. And if I set 8 cores, then there is no difference in time at all.

When I enable DMP and specify the cores when starting the calculation, I get an error:

Why? How to use all cores?

[Reno Genest]

Hello Javat,

SMP does not scale well beyond about 8 cores. So, you should not see a speedup beyond 8 cores and you may actually see speed degradation with more cores.

When you activate DMP, the MPP version of LS-DYNA is used (as opposed to SMP). MPP will scale well beyond 8 cores and it is the solver to use to utilize all your cores.

With MPP LS-DYNA you get mesXXXX files. For example, if you run on 24 cores, you will get mes0000 - mes0023 files in the working directory and the error message can be found in one or many mesXXXX files. So, you have to look at all the mesXXXX to find a meaningful error message. You can also use the following webapp to save time and extract error messages from mesXXXX automatically:

https://nagasairam112-check-dyna-errors-error-dyna-check-rq20je.streamlit.app/

 

Hopefully, you will extract a proper error message that will help you troubleshoot the problem.

You will find more information on SMP and MPP LS-DYNA here:

Microsoft PowerPoint - mpp_201305 (lstc.com)

 

Let me know how it goes.

 

Reno.

[javat33489]

Hello sir. Thanks for your reply.
Yes, I looked at the file and found an error there:

But I don't know how to fix it.

[javat33489]

Help please

[Reno Genest]

Hello javat,

You get the problem only when running MPP LS-DYNA? SMP runs fine?

Have you tried a different version of LS-DYNA?

 

Reno.

[javat33489]

Yes, SMP works well.
I use the new 2024 version.

[Reno Genest]

Try with a different version of LS-DYNA (R15.0.2 is the latest version):

LS-DYNA (user=user) Download Page (lstc.com)

username: user

password: computer

Also, try LS-RUN to run LS-DYNA MPP. 

Index (lstc.com)

 

LS-Run 1.0 tutorial (youtube.com)

 

Reno.