Possibility to run several calculations at the same time with OpenFoam?

mqsim · March 7, 2016, 06:22

Hi everyone,

I am wondering if there is a possibility to run at least two calculations at the same time. I have 8 processors that I am using to run a case. I am currently using around 8Go of RAM and I have 32Go of RAM.

Do you think it is possible to run two run two calculations at the same time without any negative impact on the calculation time?

Regards,

mqsim

Artur · March 13, 2016, 07:34

Don't suppose there's a definite answer since a lot will depend on your mesh size, decomposition, whether running steady or unsteady simulations, and hardware setup (8 physical cores or 4 with 2 threads as on intel i7, how many memory channels per processor, etc.). Best suggestion is probably to try it and see

When I run stuff on my local machine (intel i7, 16 GiB RAM) I find that for moderate mesh sizes I achieve faster solutions when only using 4 cores over all 8, which I suspect has something to do with the memory channels and how the processor handles dual threads per physical core. I suppose you could run into similar problems when running multiple simulations on the same machine at the same time but perhaps even if the individual simulations run slower you can still save time by running them in parallel?

All the best,

A

mqsim · March 16, 2016, 09:28

Hi Arthur,

Indeed, the best way to know is to try. But I wanted to know different experiences so thank you for yours!

It is true if I run several calculations at the same time, simulations run slower. I have not yet tried to use only 4 cores over all 8, I have also an intel core i7 so it could be a way to run two simulations at the same time without any negative impact on the calculation time.

Regards,

mqsim

March 7, 2016, 06:22	Possibility to run several calculations at the same time with OpenFoam?	#1
mqsim New Member Join Date: Feb 2016 Posts: 28 Rep Power: 10	Hi everyone, I am wondering if there is a possibility to run at least two calculations at the same time. I have 8 processors that I am using to run a case. I am currently using around 8Go of RAM and I have 32Go of RAM. Do you think it is possible to run two run two calculations at the same time without any negative impact on the calculation time? Regards, mqsim

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March 13, 2016, 07:34		#2
Artur Senior Member Artur Join Date: May 2013 Location: Southampton, UK Posts: 372 Rep Power: 19	Don't suppose there's a definite answer since a lot will depend on your mesh size, decomposition, whether running steady or unsteady simulations, and hardware setup (8 physical cores or 4 with 2 threads as on intel i7, how many memory channels per processor, etc.). Best suggestion is probably to try it and see When I run stuff on my local machine (intel i7, 16 GiB RAM) I find that for moderate mesh sizes I achieve faster solutions when only using 4 cores over all 8, which I suspect has something to do with the memory channels and how the processor handles dual threads per physical core. I suppose you could run into similar problems when running multiple simulations on the same machine at the same time but perhaps even if the individual simulations run slower you can still save time by running them in parallel? All the best, A

March 16, 2016, 09:28		#3
mqsim New Member Join Date: Feb 2016 Posts: 28 Rep Power: 10	Hi Arthur, Indeed, the best way to know is to try. But I wanted to know different experiences so thank you for yours! It is true if I run several calculations at the same time, simulations run slower. I have not yet tried to use only 4 cores over all 8, I have also an intel core i7 so it could be a way to run two simulations at the same time without any negative impact on the calculation time. Regards, mqsim