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Subject: Re: [OMPI devel] Any plans to support Intel MIC (Xeon Phi) in Open-MPI?
From: Christopher Samuel (samuel_at_[hidden])
Date: 2013-05-03 00:18:08

Hash: SHA1

Hi Ralph, very quick reply as I've got an SGI engineer waiting for
me.. ;-)

On 03/05/13 12:21, Ralph Castain wrote:

> So the first problem is: how to know the Phi's are present, how
> many you have on each node, etc? We could push that into something
> like the hostfile, but that requires that someone build the file.
> Still, it would only have to be built once, so maybe that's not too
> bad - could have a "wildcard" entry if every node is the same,
> etc.

We're using Slurm, and it supports them already apparently, so I'm not
sure if that helps?

> Next, we have to launch processes across the PCI bus. We had to do
> an "rsh" launch of the MPI procs onto RR's cell processors as they
> appeared to be separate "hosts", though only visible on the local
> node (i.e., there was a stripped-down OS running on the cell) -
> Paul's cmd line implies this may also be the case here. If the same
> method works here, then we have most of that code still available
> (needs some updating). We would probably want to look at whether or
> not binding could be supported on the Phi local OS.

I believe that is the case - you can login via SSH to them is my
understanding. We've not got that far with ours yet..

> Finally, we have to wire everything up. This is where RR got a
> little tricky, and we may encounter the same thing here. On RR, the
> cell's didn't have direct access to the interconnects - any
> messaging had to be relayed by a process running on the main cpu.
> So we had to create the ability to "route" MPI messages from
> processes running on the cells to processes residing on other
> nodes.


> Solving the first two is relatively straightforward. In my mind,
> the primary issue is the last one - does anyone know if a process
> on the Phi's can "see" interconnects like a TCP NIC or an
> Infiniband adaptor?

I'm not sure, but I can tell you that the Intel RPMs include an OFED
install that looks like it's used on the Phi (if my reading is correct).

- --
 Christopher Samuel Senior Systems Administrator
 VLSCI - Victorian Life Sciences Computation Initiative
 Email: samuel_at_[hidden] Phone: +61 (0)3 903 55545

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