[mcstas-users] Using mcset_ncount(nnn)

[Peter Kjær Willendrup]

Hi Uli,


As you have probably figured out yourself, our MPI-approach is quite naive in the sense that:

1) The “mother” process collects / decides the “full” ncount of the problem to be simulated (e.g. Nfull)
2) On the k used mpi processors, the partition Nfull / k is simulated

If I understand you correctly, you are asking if one could redefine the ncount in INITIALIZE?


- I guess this should in fact be possible, provided that the same Nfull is simulated over the k processors.


You will of course have to do some logic in the INITIALIZE section to up / downscale the node-dependent ncount as you propose, figuring out how many processors that are of each type and assigning the correct, scaled number locally.


Best
Peter

On 4 Jan 2021, at 14.48, Wildgruber, Christoph U. <wildgrubercu at ornl.gov<mailto:wildgrubercu at ornl.gov>> wrote:

Hi,

I have a quick question which I am not sure I found the correct answer for in the docs…

If I use 'mcset_ncount(nnn)’ in the mcstas instrument definition with the intent to improve
load balancing on a heterogeneous cluster will the run result reflect the newly set number of
source neutrons (nnn)?

Thanks,

Uli


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Peter Kjær Willendrup
Forskningsingeniør, Specialkonsulent
Næstformand for DTU Fysik LSU

DTU Physics


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Technical University of Denmark


[cid:e108e480-fcab-46e2-9531-b38165079572 at win.dtu.dk]



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