[mpich-discuss] MPI_TYPE_MAX limit using MPT

[Wei-keng Liao]

Hi, Max,

I am cc this to mpich discuss group. Hope people there can provide more thorough
answers. 

I have not run jobs on a SGI machine for a long time, but I remember I have to
increase MPI_TYPE_MAX in order to run an MPI-IO job. In collective I/O, ROMIO
uses MPI derived data type for exchanging I/O requests among processes. So,
the more processes a job runs, the bigger number MPI_TYPE_MAX should be set.

Wei-keng

On Oct 6, 2010, at 11:29 AM, Maxwell Kelley wrote:

> 
> Hello,
> 
> When running some I/O tests using MPT 1.25, I get the error
> 
> MPI has run out of internal datatype entries.
> Please set the environment variable MPI_TYPE_MAX for additional space.
> The current value of MPI_TYPE_MAX is 8192
> 
> Is this normal?  Setting MPI_TYPE_MAX to 65536 simply allowed more I/O to be performed before the error appears. The limit is reached more quickly using more processors.  Assuming that this is a case of types not being freed after use, should I just set this limit high enough that it will never be exceeded during a 12-hour batch job?
> 
> -Max
>