[mpich-discuss] MPI_TYPE_MAX limit using MPT

[Rob Ross]

Is this a global table in the sense of every process contributing to a single table? Does everyone have a copy, or is it partitioned between processes?

-- Rob

On Oct 15, 2010, at 6:50 AM, Michael Raymond <mraymond at sgi.com> wrote:

>  That's correct.  In MPT every element of a complex type like a struct
> or indexed type ends up taking up a type in the global table.  There are
> good speed reasons for this but the downside is that you sometimes need
> to preallocate a ton of space for datatypes.  This is remedied to some
> extent in MPT 2.03.  If you have any more questions about MPT you can
> contact me directly.
> 
> Wei-keng Liao wrote:
>> 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
>>> 
>> 
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> 
> -- 
> Michael A. Raymond
> Message Passing Toolkit Team
> Silicon Graphics Inc
> (651) 683-3434
>