threads, tasks and processor

[manish_manjhi7@gmail_com]

Hi,
I want to run cam5 on parallel mode using 36 processors, but i m not getting the thread and task concept. Can somebody explain how by defining the tasks and threads alone or using both (hybrid mode) i can able to use 36 processors.

 

[jedwards]

I recommmend that you start by running with MPI tasks only.   I would not expect any benefit from using threads with only 36 processors.   

 

[manish_manjhi7@gmail_com]

Thank you, i will work on it. But can you tell me what actually tasks and threads is referred to, and if i want to work on 36 processors how MPI tasks is better than OPENMP threads. -Manish Manjhi

 

[jedwards]

Tasks refer to the number of MPI elements in the model run, threads to the number of openmp threads per mpi element.   Spanning processors with threads requires that theprocessors share memory.    MPI communicates through the network and does not have this requirement.    Most large machines do not share memory across all processors andso the primary parallelization strategy in the model is MPI. 

 

[manish_manjhi7@gmail_com]

Thank you for the information. -Manish