Re: [Beowulf] PMIX and Julia?
On Tuesday, 20 November 2018 7:53:30 AM AEDT Prentice Bisbal via Beowulf wrote: > 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. Yeah, if you're launched via Slurm (for instance) you could have access to PMIx (various versions), PMI2, PMI1 (if you're earlier than 18.08) or none of the above.. For other resource managers the choices may be different. Much easier to layer yourself on top of MPI and let it handle that for you! :-) All the best, Chris -- Chris Samuel : http://www.csamuel.org/ : Melbourne, VIC ___ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
Re: [Beowulf] PMIX and Julia?
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 ___ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
Re: [Beowulf] PMIX and Julia?
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). 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/ 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 -- Chris Samuel : http://www.csamuel.org/ : Melbourne, VIC ___ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
[Beowulf] PMIX and Julia?
I am really going to show my ignorance here. I just flicked through the excellent OpenMPI BoF slides from SC18 https://www.open-mpi.org/papers/sc-2018/Open-MPI-SC18-BOF.pdf This reminded me of something I have at the back of my mind. Clearly pmix is intimately associated with MPI. On the other hand I am a fan of the Julia language, which has its own concepts of parallelism. However for a cluster spanning across multiple machines Julia currently assumes passwordless ssh will be used https://docs.julialang.org/en/v1/manual/parallel-computing/index.html#Starting-and-managing-worker-processes-1 Oooh - a bit of googling reveals that MPI can be used to communicate with the processes https://github.com/JuliaParallel/MPI.jl/blob/master/test/test_cman_mpi.jl 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. ___ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
