Re: [Starpu-devel] MPI tags limitation with Starpu

[Nathalie Furmento <nathalie.furmento@labri.fr>]

Dear Sameh,

Could you please let us know which version of StarPU you are using? The version 1.2 has a new MPI internal communication system, all the MPI messages sent and received by StarPU only use 2 different tags. You should consider using this version if you are not already doing it.

I am not sure however where the error message

"Number of descriptor available in MPI mode out of stock".

comes from. I am adding Mathieu as a recipient to get help from his side.

Cheers,

Nathalie

On 19/02/2017 07:21, Sameh Abdulah wrote:

Dear Team

I am working on chameleon and starpu to do Cholesky for large matrices on distributed systems. I need to do Cholesky for several iterations (>50) for 200K matrices. My configuration is as follows:

N: 200K

Tile Size:320

Nodes 144 (with 7 cores each)

I got this error: Too many tiles in the descriptor for MPI tags. When I checked it I found that I need to change the default values of both tag_width = 31 and tag_sep =24 on runtime_descriptor.c using this function "MORSE_user_tag_size(int tag_width, int tag_sep)". I do not know what is the correct values I need for both to handle my case. I played with different numbers but I am still having the same error and if I can avoid this error using a certain values I got another error "Number of descriptor available in MPI mode out of stock".

Please can I know the best configuration for my case and if I need to use larger thank 200K matrix how can I play with these values.

Thank you.

--Sameh Abdulah

Postdoc, ECRC, KAUST.

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