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MPI_Ibarrier: Crazy?

September 15, 2012 at 4:32 am PST

Most people’s reactions to hearing about the new MPI-3 non-blocking “barrier” collective think: huh?

Why on earth would you have a non-blocking barrier?  The whole point of a barrier is to synchronize — how does it make sense not to block while waiting?

The key is re-phrasing that previous question: why would you block while waiting?

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MPI progress

July 26, 2012 at 6:20 pm PST

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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MPI-3 voting: results

May 31, 2012 at 5:00 am PST

Last March’s MPI Forum meeting was the last meeting to get a “formal reading” of proposals into MPI-3. Some were quite controversial. Some ended up being withdrawn before the next meeting.

This week’s Forum meeting in Japan saw the first vote (out of two) for each the surviving proposals from the March meeting (see the full voting results here). Some continued to be quite controversial. Some didn’t survive their first votes (doh!). Others narrowly survived.

Here’s a summary of some of the users-will-care-about-these proposals, and how they fared: Read More »

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The last new things in MPI-3

March 28, 2012 at 5:15 am PST

I know we’ve been talking about new MPI-3 things for forever.  But this is the last list of new things.

I promise.

Really.

I can say this with certainly because the Forum’s March meeting was the deadline for all new proposals to make it into the MPI-3 standard.  Anything else will have to be in MPI-<next> (where <next> may be 3.1, or 4, or …11.  Shrug).

Because of the deadline, we had a blizzard of proposals finally get into shape to be presented to the entire Forum.  Let’s talk about some of the more interesting ones…

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New Fortran MPI bindings are “in”! And other MPI-3 stuff…

March 26, 2012 at 8:33 am PST

As of March 7, 2012, the new “use mpi_f08″ bindings have been officially voted in to the MPI-3 standard.

Woo hoo!!

A few other minor corrections made it into MPI-3 at the same meeting, but they’re boring / not worth discussing.

What is worth discussing, however, are some proposals that passed their first (of two) formal votes to make it into MPI-3 at that same meeting:

Let’s give a few details on each of these…

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