# Computing on multiple notes with multiple cores

조회 수: 4 (최근 30일)
Paul Muster 2023년 11월 6일
댓글: Paul Muster 2023년 11월 9일
Hello,
I have a code with the following structure:
for ... % Split between multiple nodes
parfor ... % Split betwenn mutliple cores
...
end
end
Is it possible to tell MATLAB, that it has to split the for-Loop between the nodes? Or does that MATLAB automatically if I use parfor 2 times? I.e.
parfor ... % Split between multiple nodes
parfor ... % Split betwenn mutliple cores
...
end
end

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### 채택된 답변

Matt J 2023년 11월 9일
The problem is, that the outer loop has 10 repetitions and the inner loop 50 repetitions
Combine the loops into one, i.e., instead of
for i=1:10% Split between multiple nodes
parfor j=1:50 % Split betwenn mutliple cores
...
end
end
parfor k=1:10*50
[i,j]=ind2sub([10,50],k);
...
end
##### 댓글 수: 2없음 표시없음 숨기기
Paul Muster 2023년 11월 9일
I have to check, if I have to change my used data structure for that. But thank you, that's an option.
Matt J 2023년 11월 9일
You're welcome, but if you find that it works (it should), please Accept-click the answer.

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### 추가 답변 (1개)

Harald 2023년 11월 6일
Hi Paul,
you can only have one level of parallelization, thus no nested parfor statements within a single script / function.
If the parallel pool that runs the parfor has cores on multiple nodes, they will automatically be used. While there might be reasons to parallelize the inner loop, I typically first try to parallelize the outer loop.
Best wishes,
Harald
##### 댓글 수: 5이전 댓글 3개 표시이전 댓글 3개 숨기기
Harald 2023년 11월 9일
Hi Paul,
in many cases, there may not be a problem of parallelizing the inner loop as you initially suggested.
Matt J has offered a nice alternative to thinking about which loop to parallelize.
My understanding is that your main question was if your code was going to use multiple cores on multiple nodes, and the answer to that was: If the parallel pool that runs the parfor has cores on multiple nodes, they will automatically be used.
Please let me know if I can be of further help.
Best wishes,
Harald
Paul Muster 2023년 11월 9일
Ok, thank you very much!

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