Learning Forum

[ge suo]

Hello developers！Why does this prompt appear？My computer memory is 96G，The virtual memory is set to about 300G.LS-RUN is set to set memory automatically,How can I solve this problem？

 

Best wishes！

[Ram Gopisetti]

Hi Virtual memory should not be considered, only physcial memmory is to be considered and ou need to set the memory below 95GB not greater than it to avoid such warning. 

Cheers, Ram 

[ge suo]

Hello Ram, thank you very much for your answer！I set the memory value according to your method, but problems still occur,You can see the picture，This problem has been bothering me for several days😭

For instance，When I use 10 cores for calculation, the prompt box will not appear, and the calculation time: 20h

                       When I use 16 cores for calculation, this prompt box will appear, and the calculation time: 30h

I don't know how to solve this problem.

Best wishes！

[Reno Genest]

Hello,

How much memory do you really need? You could use memory= and memory2= on the expression line (memory= is already set).

 

This should allow you to use less total memory for this problem.

Here is more information from our knowledge database:

"

"memory=" specifies the memory for the 1st core where decomposition is performed.
"memory2=" specifies memory for the 2nd and subsequent cores.  
If "memory2=" is not specified, than all the cores allocate memory according to "memory=".   

A suggested procedure is to over-allocate memory for a short trial run, that is, take a conservative stab at how much memory to allocate.   You'll then know from the d3hsp file what the minimum requirements for memory and memory2 and can use that knowlege in the full run.  Look for the words "Memory required to begin solution" in d3hsp.

The memory you allocate for a core should not exceed roughly 80% of the physical memory.    As an example, let's say you have 8 Gb memory per core.   If you run double precision, there's 8 bytes per word so the max memory you should attempt to allocate for a double precision run is 

80% of  (8e9 bytes)/(8 bytes per word) = 8e8 words

Thus, as an upper bound, you'd set memory=800m in the trial run.  Again, this is just to get the actual memory requirements for the full run.

"

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

https://ftp.lstc.com/anonymous/outgoing/support/PRESENTATIONS/mpp_201305.pdf


Also, have a look at appendix O in the LS-DYNA user manual I:

https://lsdyna.ansys.com/manuals/




Let me know how it goes.


Reno.

[ge suo]

Thank you most sincerely,my friend.I tried the method you said, and it worked.I don't think I have any problems now。

Finally, I would like to thank you again for helping me solve this problem.

Best wishes！

 

[Reno Genest]

Great!

Have a good  day!

 

Reno.