[ofiwg] DS/DA Runtime Model Discussion

Underwood, Keith D keith.d.underwood at intel.com
Thu Feb 11 04:18:07 PST 2016

I don't typically make it to the DS/DA calls, so I am missing a bit of context.  Could you expand on what you mean by serialization/locking a little bit more?  

> -----Original Message-----
> From: ofiwg-bounces at lists.openfabrics.org [mailto:ofiwg-
> bounces at lists.openfabrics.org] On Behalf Of Oucharek, Doug S
> Sent: Wednesday, February 10, 2016 6:37 PM
> To: Paul Grun <grun at cray.com>
> Cc: ofiwg at lists.openfabrics.org
> Subject: [ofiwg] DS/DA Runtime Model Discussion
> This email is a followup to my comment in a previous DS/DA call about the
> runtime model being an important part of the DS/DA definition.
> MPI seems to be the dominate user of fabrics in HPC.  As such, they have a huge
> impact on the design of the runtime model being followed by fabric developers
> and corresponding middleware (what I consider OFED/verbs, libfabrics, and
> DS/DA).  Currently, they seems to be pushing for bare metal access from the
> providers leaving the work of serialization/locking to the middleware or the
> applications themselves.
> If DS/DA follows libfabrics in its development, I am concerned that the bare
> metal mindset will dominate here as well and that will leave “application
> anarchy” with regards to how serialization/locking is being done.  Mitigating the
> strategy of fabric users is something I would expect from the providers (the one
> common access point regardless of middleware).  The MPI push was to get this
> common point to back off and leave serialization/locking to the upper layers
> but we now do not have a common point to coordinate competing access to
> the fabric.
> Should it not be a part of the middleware (libfabrics and DS/DA) to at the very
> least, put demands upon the providers so a common strategy for
> serialization/locking can be enforced for a specific fabric so the apps, like
> Lustre, don’t have to make significant code changes to get reasonable
> performance out of the fabric?  If we have to make significant changes for each
> new fabric released, the value of the middleware (be it OFED, libfabrics, or
> DS/DA) is severely diminished and we might as well just access the fabric drivers
> directly.
> Discussion?
> Doug
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