mpirun actual number of processors used
I am starting programming on an OpenMPI managed cluster. I use the following command to run my executable:
mpirun -np 32 file
Now what I understand is that 32 specifies the number of processes that should be cre开发者_StackOverflow社区ated. They may be created on the same processor. Am I right?
I am noticing increasing time for execution with increase in the number of processes. Could the above be a reason for this?
How do I find out the execution and scheduling policy of the cluster?
Is it correct to assume that typically the cluster I am working on will have many processes running on each node just as they run on my PC.
I would expect your job management system (which is ?) to allocate 1 MPI process per core. But that is a configuration matter and your cluster may not be configured as I expect. Can you see what processes are running on the various cores of your cluster at run time ?
There are many explanations for increasing execution time with increasing numbers of processes, several good ones which include the possibility of one-process-per-core. But multiple processes per core is a potential explanation.
You find out about the policies of your cluster by asking the cluster administrator.
No, I think it is atypical for cluster processors (or cores) to execute multiple MPI processes simultaneously.
精彩评论