Run multiple cases simultaneously in parallel?

joshmccraney · April 16, 2020, 22:14

Hi FOAMers!

I have 16 cores available, and would like to run 4 different cases simultaneously, each on 4 cores. Is this possible? Is it as simple as simply running

Code:

mpirun -np 4 interFoam -parallel

or do I need to tell the system which 4 to use so that it's using all 16?

mzzmrt · April 17, 2020, 05:31

I guess you can. Just open four terminals run each case simultaneously.

Of course you have to partition the grids first for parallel processing.

joshmccraney · April 17, 2020, 18:50

Quote:

Originally Posted by mzzmrt

I guess you can. Just open four terminals run each case simultaneously.

Of course you have to partition the grids first for parallel processing.

So the computer is just smart enough to know not to reuse old cores?

mzzmrt · April 18, 2020, 04:26

I made a test and understood that my guess is wrong!

mzzmrt · April 19, 2020, 18:13

Well, just found the solution. An additional command "cpu-set" is needed:

mpirun -np 2 --cpu-set 0-3 pisoFoam -parallel (for assigning fist four cores)

mpirun -np 2 --cpu-set 4-7 pisoFoam -parallel (for assigning second four cores)
so on...

lebc · April 20, 2020, 12:13

You can also use the "--bind-to socket" or "--bind-to core" option, it works fine!

April 16, 2020, 22:14	Run multiple cases simultaneously in parallel?	#1
joshmccraney Senior Member Josh McCraney Join Date: Jun 2018 Posts: 220 Rep Power: 8	Hi FOAMers! I have 16 cores available, and would like to run 4 different cases simultaneously, each on 4 cores. Is this possible? Is it as simple as simply running Code: mpirun -np 4 interFoam -parallel or do I need to tell the system which 4 to use so that it's using all 16?

April 19, 2020, 18:13		#5
mzzmrt Senior Member Join Date: Mar 2014 Posts: 112 Rep Power: 12	Well, just found the solution. An additional command "cpu-set" is needed: mpirun -np 2 --cpu-set 0-3 pisoFoam -parallel (for assigning fist four cores) mpirun -np 2 --cpu-set 4-7 pisoFoam -parallel (for assigning second four cores) so on... joshmccraney likes this. Last edited by mzzmrt; April 20, 2020 at 04:14.

April 20, 2020, 12:13		#6
lebc Member Luis Eduardo Join Date: Jan 2011 Posts: 85 Rep Power: 15	You can also use the "--bind-to socket" or "--bind-to core" option, it works fine! joshmccraney likes this.

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April 17, 2020, 05:31		#2
mzzmrt Senior Member Join Date: Mar 2014 Posts: 112 Rep Power: 12	I guess you can. Just open four terminals run each case simultaneously. Of course you have to partition the grids first for parallel processing.

April 18, 2020, 04:26		#4
mzzmrt Senior Member Join Date: Mar 2014 Posts: 112 Rep Power: 12	I made a test and understood that my guess is wrong!