Config Setting for Simulate 3.0

[BillChapman]

I am running Creo Parametric/Simulate 3.0 M070.  We recently upgraded our PCs and we now have 16Gb RAM, 500 GB Solid State Hard drive running Win 7 64.   The processor is an intel i7-4790 @ 3.6 GHz.

What config.pro settings need to be set to optimize Simulate performance?  Any recommendations of specific of values for the settings below or are the default values OK for our setup?

cpus_to_use

sim_solver_memory_allocation

Thanks in Advance.

Bill

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[sdensberger]

Tad gives an excellent explanation here: https://community.ptc.com/t5/System-Administration/Mechanica-limiting-critical-hardware/td-p/118895#160574

[ehaenen]

Thew limits that Tad give are outdated however.

We've had numerous discussions here, but no real clue to current limts (Tad's post is from 2011)

He writes:

• If you use a 32-bit Window OS, the maximum amount of memory that any one application can use is 3.2 GB.
• Solram is currently limited to a maximum of 8 GB. This maximum will be increased in a future release of Mechanica.

The maximum of memory that one application can use on a 64 bit Window OS is much much more than 3.2 GB, we've seen 60 GB used by Creo-simulate

Solram seems to be limited to 16 Gb

[sdensberger]

While the answer is dated, the information really isn't. You'll notice that Tad focuses on discussing the different scenarios (instead of just giving a number) because what the "best" is depends on the specifics of the problem.

[BillChapman]

Yes, sim_solver_memory_allocation seems to be situation specific, perhaps a better answer is leave sim_solver_memory_allocation set to the default unless you have a need to limit this.  Tad's explanation is good to understand proper usage on this. 

It seems that simulate will use the max number of cores as default, so I am not sure not sure what the purpose of "cpus_to_use".   This is also probably best left set the the default.

[JonathanHodgson]

I would suggest that the main point of using fewer CPUs (or threads) is to keep the system more responsive for other tasks during an analysis.

Particularly with a hyperthreaded CPU (4 physical cores, reporting 8 cores to Windows) using only as many threads as physical cores seems to yield most of the performance.  Note that with more threads, reported CPU time increases due to overheads, but total elapsed time (ET) reduces only very slightly.

I hadn't seen the 'cpus_to_use' option - I picked up an older one, which didn't work properly in 2.0:

"sim_run_num_threads" config option misbehaving?

[JonathanHodgson]

Interesting - I've never played with the sim_solver_memory_allocation (hidden) config option, although interestingly our set-up has it set to 512 instead of the reported default of 128, despite not being apparent in the config.pro.

Searching the site here, there's a recommendation to set it to 8192:

PTC Creo Simulate Update 10 Tips and Tricks - PTC Community (with some other interesting hidden options too - see P13)

and a report of setting it to 65536 with no apparent effect:

Re: What do you do when your model reaches Simula... - PTC Community

I've just run a couple of analyses myself (taking between 650 MB and 7 GB of RAM as reported by Task Manager - or 13.25 GB in all cases as reported by Mechanica) and I've seen no significant differences between settings of 128 and 8192.  The run-to-run variations are greater!

I'll continue to not worry about it, then...

[BillChapman · Accepted solution]

There does not seem to be a clear answer if these config settings actually improve performance.  These are not hidden settings in Creo 3.0.  Following the advise in one of the threads and in the above presentation (PTC Creo Simulate Update 10 Tips and Tricks) I set:

sim_solver_memory_allocation 8192  (which is 1/2 of the physical memory)

Although it was not mentioned in the presentation I did set:

cpus_to_use 4

Yet to be determined if things are better or indifferent with these settings.

[BillChapman]

I wanted to share that a "best practice article" was just released on this subject.  Link is listed below.  The recommended setting of sim_solver_memory_allocation is between 20-50% of physical RAM.

The more specific guidelines are:

• For a static or prestress analysis with the direct solver, block solver RAM should not exceed one-half of your machine RAM. In this case, the RAM allocation for element data has no effect and the default value is the ideal choice.
• For a static or prestress analysis with the iterative solver, block solver RAM and the RAM allocation for element data together should not exceed three-quarters of your machine RAM. A recommended starting point is to allocate one-tenth of your machine RAM for your block solver and one-half of your machine RAM for element data.
• For a modal, prestress modal, or buckling analysis, block solver RAM and the RAM allocation for element data together should not exceed one-half of your machine RAM. A recommended starting point is to allocate one-quarter of your machine RAM for the block solver and one-quarter for element data.
• Block solver RAM and the RAM allocation for element data together should never exceed three-quarters of your machine RAM.
• You can find specific information about the block solver RAM and the RAM allocation for element data in the element calculations section of the study/study.pas file, located in the directory for output files.

https://support.ptc.com/appserver/cs/view/solution.jsp?source=subscription&n=CS51761

http://help.ptc.com/creo_hc/creo30_sim_hc/usascii/#page/sim/simulate/run/structure/reference/memory-usage-different-scenarios.html

[JonathanHodgson]

Aha, so sim_solver_memory_allocation appears to set the default for the SOLRAM setting.

"You can change this default value by setting the config.pro option sim_solver_memory_allocation to a different number."

This explains why I wasn't seeing any meaningful differences, as I always set the SOLRAM value manually!

What I can't see in the links is how to control "the RAM allocation for element data" - presuming that "block solver RAM" is SOLRAM.