Thank you so much Hui. Really appreciate it. I now understand it.
From:
Zhou, Hui <zhouh@anl.gov>
Date: Monday, July 1, 2024 at 4:37 PM
To: Niyaz Murshed <Niyaz.Murshed@arm.com>, discuss@mpich.org <discuss@mpich.org>, Jenke, Joachim <jenke@itc.rwth-aachen.de>
Cc: nd <nd@arm.com>
Subject: Re: Custom rank for processes
Yes, you can use rankmap to simply list out the node assignment for each rank. "-rankmap (vector,1,1,0,0,0)" is a list of 5 node ids, one for each rank. So rank 0 gets node 1, rank 1 gets node 1, rank 2 gets node
0, and so on.
The -hosts options is convenient if you have somewhat uniform assignment. If you want arbitrary assignment, just use -rankmap option.
--
Hui
From: Niyaz Murshed <Niyaz.Murshed@arm.com>
Sent: Monday, July 1, 2024 4:30 PM
To: Zhou, Hui <zhouh@anl.gov>; discuss@mpich.org <discuss@mpich.org>; Jenke, Joachim <jenke@itc.rwth-aachen.de>
Cc: nd <nd@arm.com>
Subject: Re: Custom rank for processes
Sorry to bother you again with silly questions. How do I read the below : -rankmap (vector,1,1,0,0,0) I have 5 processes. 1 1 => means node1 will get first 2 processes
? -hosts 192. 168. 2. 100: 2,192. 168. 2. 200: 3
: this will give 2 process in
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Sorry to bother you again with silly questions.
How do I read the below :
-rankmap (vector,1,1,0,0,0)
I have 5 processes. 1 1 => means node1 will get first 2 processes ?
-hosts 192.168.2.100:2,192.168.2.200:3 : this will give 2 process in 100 and 3 in 200 .. Still won’t be able to specify which ranks goes to which node. Rank0 will be on node 100 .. what If I want Rank0 on node
200?
From:
Zhou, Hui <zhouh@anl.gov>
Date: Monday, July 1, 2024 at 4:09 PM
To: Niyaz Murshed <Niyaz.Murshed@arm.com>, discuss@mpich.org <discuss@mpich.org>, Jenke, Joachim <jenke@itc.rwth-aachen.de>
Cc: nd <nd@arm.com>
Subject: Re: Custom rank for processes
> root@ampere-altra-2-1:/# mpirun -n 5 -bind-to user:10,11,12,13 -hosts 192.168.2.200,192.168.2.100 /mpitutorial/tutorials/mpi-hello-world/code/mpi_hello_world
Hello world from processor ampere-altra-2-1, rank 1 out of 5 processors
Hello world from processor ampere-altra-2-1, rank 3 out of 5 processors
Hello world from processor dpr740, rank 0 out of 5 processors
Hello world from processor dpr740, rank 4 out of 5 processors
Hello world from processor dpr740, rank 2 out of 5 processors
> -bind-to user:10,11,12,13
> This would mean on host 192.168.2.100
> P0=>10 , P2=>11
> This would mean on host 192.168.2.200
> P0=>10 , P2=>11, P3=12
> Is this correct understanding ? Is it also possible to say which rank process will be pinned to which core ?
Yes, that is correct. The ranks are assigned to hosts as shown in the hello world output.
> About the rankmap:, trying to understand if I can select where a particular rank would be from > list of hosts. Currently, the first host in the list always get rank0.
> Can I specify the below ranks?
> mpirun -n 5 -bind-to user:10,11,12,13 -hosts 192.168.2.200,192.168.2.100 /mpitutorial/tutorials/mpi-hello-world/code/mpi_hello_world
>
> Hello world from processor ampere-altra-2-1, rank 1 out of 5 processors => rank0
> Hello world from processor ampere-altra-2-1, rank 3 out of 5 processors. => rank1
> Hello world from processor dpr740, rank 0 out of 5 processors =>rank2
> Hello world from processor dpr740, rank 4 out of 5 processors =>rank3
> Hello world from processor dpr740, rank 2 out of 5 processors =>rank4
Yes. You can use "-rankmap (vector,1,1,0,0,0)". Alternatively, you can use "-hosts 192.168.2.100:2,192.168.2.200:3", the colon syntax specifies how many processes you want to assign to each host.
--
Hui