[mpiwg-p2p] Next meeting: 14th April 2014 11am Central US

[Daniel Holmes]

Hi all,

The next point-to-point teleconference will be on Monday 14th April 2014 
at 11am Central US via webex.

Connection details are on the p2p wiki.

Agenda:
1) Streams: I have some notes - see below - from a discussion last week 
with Bill Gropp, Torsten (et al from the EPiGRAM project)
2) Receive_reduce
3) Arecv
4) AOB (= any other business)

Cheers,
Dan.

Streams
=======
QCDOC developers want persistent channel semantics; actually use 
one-sided, multi-value variables
Breaking message boundaries enables pipe-lining - makes it fundamentally 
different to RMA?
Libraries exist to do this - what are they?
Streaming is well defined in OpenSPL
Papers from the MPI-2 era (about RMA) suggest writing papers on this and 
getting feedback
Reach out to other communities, e.g. SKA - Square Kilometre Array
Should this be added to MPI or added as a library on top - does this 
need small enabling changes
Bill suggests we craft a broad-visibility paper
Affects the discussion on Arecv, which would be handled by streams?
Getting MPI to manage/allocate memory (as in Arecv) is dangerous and bad

Flow-control
============
May just be remote notification and a sequence of messages that remove 
the need for local notification - reduces protocol messages (from 3 to 1 
per message)
Integral part of streaming - turns global flow-control problem into 
local buffer management
May address load-imbalance? Hmm

-- 
Dan Holmes
Applications Consultant in HPC Research
EPCC, The University of Edinburgh
James Clerk Maxwell Building
The Kings Buildings
Mayfield Road
Edinburgh, UK
EH9 3JZ
T: +44(0)131 651 3465
E: dholmes at epcc.ed.ac.uk

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