Cisco Blogs


Cisco Blog > High Performance Computing Networking

SC’11, Open MPI BOF, and 10 petaflops!

November 6, 2011 at 6:07 am PST

SC'11 logoI’m sure most everyone has heard already, but the K supercomputer has been upgraded and now reaches over 10 petaflops.  Wow!

10.51 petaflops, actually, so if you round up, you can say that they “turned it up to 11.”  Ahem.

We’ll actually have Shinji Sumimoto from the K team speaking during the Open MPI BOF at SC’11.  Rolf vandeVaart from NVIDIA will also be discussing their role in Open MPI during the BOF.

We have the 12:15-1:15pm timeslot on Wednesday (room TCC 303); come join us to hear about the present status and future plans for Open MPI.

Tags: , ,

The MPI C++ Bindings

October 31, 2011 at 6:06 am PST

What a strange position I find myself in: the C++ bindings have become somewhat of a divisive issue in the MPI Forum.  There are basically 3 groups in the Forum:

  1. Those who want to keep the C++ bindings deprecated.  Meaning: do not delete them, but do not add any C++ bindings for new MPI-3 functions.
  2. Those who want to un-deprecate the C++ bindings.  Meaning: add C++ bindings for all new MPI-3 functions.
  3. Those who want to delete the C++ bindings.  Meaning: kill.  Axe.  Demolish.  Remove.  Never speak of them again.

Let me explain.

Read More »

Tags: ,

Shared Receive Queues

October 25, 2011 at 5:00 am PST

In my last post, I talked about the so-called eager RDMA optimization, and its effects on resource consumption vs. latency optimization.

Let’s talk about another optimization: shared receive queues.

Shared receive queues are not a new idea, and certainly not exclusive to MPI implementations.  They’re a way for multiple senders to send to a single receiver while only consuming resources from a common pool.

Read More »

Tags: , , ,

MPI tradeoffs: space vs. time

October 22, 2011 at 7:42 am PST

@brockpalen asked me a question in Twitter:

@jsquyres [can you discuss] common #MPI implementation assumptions made for performance and/or resource constraints?

Good question.  MPI implementations are full of trade-offs between performance and resource consumption.  Let’s discuss a few easy ones.

Read More »

Tags: , ,

More MPI-3 newness: const

October 16, 2011 at 5:00 am PST

Way back in the MPI-2.2 timeframe, a proposal was introduced the add the C keyword “const” to all relevant MPI API parameters.  The proposal was discussed at great length.  The main idea was twofold:

  • Provide a stronger semantic statement about which parameter contents MPI could change, and which it should not.  This mainly applies to user choice buffers (e.g., the choice buffer argument in MPI_SEND).
  • Be more friendly to languages that use const(-like constructs) more than C.  The original proposal was actually from Microsoft, whose goal was to provide higher quality C# MPI bindings.

Additionally, the (not deprecated at the time) official MPI C++ bindings have had const since the mid-1990s — so why not include them in the C bindings?

Read More »

Tags: , ,