[mpich-discuss] PMI documentation

[Ashley Pittman]

On Thu, 2009-08-27 at 13:28 -0500, Pavan Balaji wrote:
> PMI-1 does not standardize the wire 
> protocol, so there are different implementations for it including the 
> default simple PMI protocol, smpd PMI protocol and slurm PMI protocol. 

That's frustrating, the wire protocol with mpd is very easy to use.  I'm
looking at it for two reasons and one of them is for a application
written in perl where it's nearly impossible to interface with the C api
but really easy to use the wire protocol.

> I also want to point out that our current effort is on PMI-2 (the second 
> generation of the PMI interface). This is still being formulated, so 
> things might (and will likely) change based on feedback on various 
> folks. You can find more information on PMI2 on the below links:
> 
> http://wiki.mcs.anl.gov/mpich2/index.php/PMI_v2_Design_Thoughts
> http://wiki.mcs.anl.gov/mpich2/index.php/PMI_v2_API
> http://wiki.mcs.anl.gov/mpich2/index.php/PMI_v2_Wire_Protocol

I'll take another look at this when there is something tangable I can
play with.  One thing that would be nice is to be able to connect into
the PMI namespace from outside the parallel job, padb for example needs
to do a "gather" of hostnames and port numbers on startup and it's
currently difficult to export this to the process that spawned the
mpdrun command.

Ashley,

-- 

Ashley Pittman, Bath, UK.

Padb - A parallel job inspection tool for cluster computing
http://padb.pittman.org.uk