Learning Forum

[NireshBehari]

Hi

I have a quad core HP Spectre and would like to make the solution processing time to be faster. How do I go about resetting the number of processors from 2 to 4?

 

regards

Niresh

 

[peteroznewman]

In Mechanical, Tools, Solve Process Settings..., My Computer, Advanced...

Though you are in a particular model, it is a setting for the computer, not just the model you are in, so it will persist for all other models.

You can repeat on My Computer, Background if you submit for Background solve

[NireshBehari]

Many thanks

I went to Tools--->Mechanical --->and adjusted the cores to 4

I also went to Mechanical ADL and did the same

I could not find "My Computer, Background"

I also don't see "Advanced Properties"

Remember I downloaded version 18.2

 

[peteroznewman]

You don't see a list like this in Mechanical, Tools, Solve Process Settings?

[NireshBehari]

Hi Peter

No I am trying to find that window, which you are describing 

i need to go to Tools----> Options---->Mechanical------>and then adjust the number of cores

can you please make a print screen of the Windows prior to getting to Solve Process Settings, since I cannot find that window?

And write a few more steps for me.....just to be sure

many thanks

Niresh

 

 

[peteroznewman]

Hi Niresh, here are the screen snaps from start to finish. You first have to open any model in Mechanical.

Click Advanced...

Select My Computer, Background

Click Advanced...

Regards,
Peter

[guimilan]

Hi Peter, I'm having some issue running Mechanical on multiple cores as well.

I'm running it on a cluster and if I got it right, when I set the number of cores from Tool > Solve Process Settings > Advanced..., that setting is saved for the computer I'm using at the moment of the modify, not for the specific workbench project, so if I import the file in a different machine, the setting will return to its default value (2), correct?

I prepare the file for the simulation on my laptop, then load it on the cluster, where simulations run only on 2 cores. I tried also to set the number of cores as described in this link https://www.sharcnet.ca/Software/Ansys/16.2.3/en-us/help/ans_dan/Hlp_G_ADVPARA_1.html, but with no luck. Do you have any suggestion I could try?

Best regards

[peteroznewman]

@guimilan,

It's best for you to open a New Discussion so you are notified of replies. The original poster of this discussion is going to get a notification instead of you.

If you move a workbench archive to a different computer, that computer will have a setting for number of cores, it will not automatically default to 2 cores.

Here is an old thread on how to submit to a linux cluster.

I would add that there is a flag on the command line -np 8 that says how many processors to use, in this example, it is 8 cores.

/home/ANSYS Inc/v170/ansys/bin/Linux64/ansys170 -b -i input.dat -o solve.out -np 8

[KartiSinghFreeman]

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peteroznewman do you still know where that old thread is? I'm currently having the same issue as guimilan is with my cluster solver only using two cores.

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[peteroznewman]

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KartiSinghFreeman

You are out of luck on the old thread. Did you try the command line with the -np 8 flag?

/forum/discussion/27032/many-broken-links

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[KartiSinghFreeman]

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peteroznewman I haven't tried using -np when running runwb2.

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[KartiSinghFreeman]

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peteroznewman I tired with no luck at all. This is frustrating because on my local I can run more cores than I can on the HPC cluster, and there is no documentation from ANSYS that helps with figuring this out.

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[peteroznewman]

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KartiSinghFreeman

You don't use -np when running runwb2.

You use -np when running the ansys solver as shown in this command line example from Version 17 of ANSYS.

/home/ANSYSInc/v170/ansys/bin/Linux64/ansys170 -b -i input.dat -o solve.out -np 8

If you start the Mechanical APDL Product Launcher from the Window Start Menu, it provides you the command line after you fill out all the items you want in the GUI.

I don't agree that there is no documentation from ANSYS. Simply open the ANSYS Help system then copy/paste the following URL into the address bar of the browser running ANSYS Help and you will land on the Batch Mode page.

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v212/en/ans_ope/Hlp_G_OPE3_4.html

Here is the page with the command line parameters such as -np

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v212/en/ans_ope/Hlp_G_OPE3_1.html

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[KartiSinghFreeman]

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peteroznewman I've got a large workbench file with a number of simulations that I run in batch mode with a journal file to update on a HPC.

Despite setting all the relevant command lines in Mechanical APDL when it is run in batch mode it won't use more than two cores. It's absolutely frustrating as ANSYS doesn't provide much if any information on workbench scripting.

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[peteroznewman]

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KartiSinghFreeman

ANSYS does provide information on workbench scripting, there is a whole section in the ANSYS Help on that topic, complete with examples!

What version of ANSYS are you running? What licenses are available to run ANSYS? Are the licenses you use locally the same ones that are available on the HPC? Are there cluster commands that must be issued to be granted more than 2 cores?

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[KartiSinghFreeman]

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peteroznewman I gave up on Workbench for solving as it doesn't work.

I'm just using Mechanical APDL through command line and then loading the results files back through Workbench for visualisation.

I had to overcome some MPI related issues that weren't documented within ANSYS's documentation, those issues may be why Workbench is broken for solving, or it could be unrelated issues that aren't covered within their documentation.

Either way what happens when solving with Workbench is that it defaults to two cores on the cluster, no idea why but it is what it is. Mechanical APDL command line is the only way to overcome this as you can run the command line through the terminal.

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[peteroznewman]

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KartiSinghFreeman

I don't run Workbench on the Linux HPC cluster at work, I use the Remote Solve Manager from my Windows desktop. You can read about it in the discussion linked to below:

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[KartiSinghFreeman]

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peteroznewman RSM is not installed on the cluster I use so that was never an option I could lean on.

I did read that thread originally but the solver was failing due to MPI issues in ANSYS which I managed to resolve utilising Intel's documentation on MPI.

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