[Beowulf] PMIX and Julia?

[Prentice Bisbal]

On 11/18/18 3:16 PM, Chris Samuel wrote:

> On Monday, 19 November 2018 6:35:56 AM AEDT John Hearns via Beowulf wrote:
>
>> What I am really asking is will pmix be totally necessary when running on
>> near-exascale systems, or am I missing something? My thoughts are should
>> the Julia world be looking at mpix adaptations? If someone with a clue
>> about pmix could enlighten me I would be grateful.
> My (limited) understanding of this is that PMI* is an MPI wire-up protocol, in
> other words a mechanism for the MPI ranks to discover each other, set up
> communications and also talk to the resource scheduler (if present).
That is my understanding, too, PMI is meant to be an abstraction layer 
between the resource manager and the different parallel processes. I 
would imagine if this abstraction is good for MPI, it could be good for 
other paradigms, like Julia, too. Conceptually, I don't think there's 
anything preventing it from being used for Julia. In reality, it depends 
on how general the API is. That's based on my understanding of PMI, of 
which I am admittedly *not* an expert.
>
> There's a handy little description of PMI (v2 in this case) here:
>
> https://wiki.mpich.org/mpich/index.php/PMI_v2_API
>
> The PMIx website (along with standards documents etc) here:
>
> https://pmix.org/

Here's another good paper on PMI:

http://www.mcs.anl.gov/papers/P1760.pdf

>
> My instinct is that it might be better for Julia to sit on MPI and let it
> handle this for it, rather than have to know about PMI2/PMIx itself..
>
> All the best!
> Chris