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MPI-3.0: What’s the holdup?

A few people have asked me questions about MPI-3 recently, such as:

  1. What took so long?
  2. Why isn’t another draft version of MPI-3.0 available yet?
  3. When do you expect the final version of the MPI-3.0 document to be available?
  4. When do you expect MPI-3.0 implementations to be available?

These are all good questions.  Let me answer each of them individually…

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MPI progress

From my blog post about the upcoming MPI-3 draft spec, Geoffrey Irving asked a followup question:

Can you describe the difference between the current situation and true background progression? Does the lack of background progression mean having to occasionally explicitly relinquish control to MPI in order to let one-sided operations proceed? Once true background progression is in place, would it involve extra threads and context switching, or use some other mechanism?

A great question.  He asked it in the context of the new MPI-3 one-sided stuff, but it’s generally applicable for other MPI operations, too (even MPI_SEND / MPI_RECV).

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Gettings towards an MPI-3.0 draft

I’ve been a bit tardy with my blogging responsibilities of late; but only because I’ve been swamped with MPI stuff.  Honest!

This past week, the MPI Forum met in Chicago and had a huge text-merging party.  Specifically, we took all the MPI-3 proposals that had passed and actually merged their text into a single document.  We did this in parallel (get it?) by dividing up the tickets and chapters among all the meeting participants.  It was quite amazing to watch, actually.  :-)

The merges resulted in a few conflicts here and there, a probably-inevitable set of LaTeX issues, some “Hey, why isn’t the Subversion server responding?” complaints, and some last minute, “Hey, that doesn’t look quite right…”-isms.

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EuroMPI 2012 Call for Participation

EuroMPI 2012 – the prime meeting for researchers, developers, and students in message-passing parallel computing with MPI (and related paradigms) – calls for active participation in the conference which will take place from September 23rd to September 26th in Vienna, Austria, at the Austrian Academy of Sciences.

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Hardware vs. software: user questions (part 2)

In my prior blog entry, I answered the first of Durga C.’s questions to me.  Here’s all three of his questions:

  1. What is the role of the hardware in an RDMA transaction?  In other words, why does one need special hardware (e.g., InfiniBand, iWARP, RoCE, etc.) hardware to do RDMA as opposed to a “normal” Ethernet NIC? (see prior blog entry)
  2. Further, can you explain why pure software solutions (e.g., Open-MX) are better than nothing when you don’t have hardware support?
  3. Also, what is the difference between “RDMA” and “RMA”?

Let’s explore the last two of those questions. Read More »

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