[molpro-user] values for --tuning-mpplat and --tuning-mppspeed

[Gershom (Jan) Martin]

Dear Molpro gurus:

What would be sensible values for --tuning-mpplat and --tuning-mppspeed between cluster nodes with an Infiniband 4-lane QDR (fully nonblocking) interconnect?

What about FDR?

The defaults in the distribution Linux/Intel binary  are apparently

--tuning-mpplat 3 and --tuning-mppspeed 1600

The old mpptune.com<http://mpptune.com> script (no longer included with M2015, presumably obsolete) give latencies WAY in excess of this, even when run within a single node.

I tried running an 8-box job (water tetramer CCSD(T)-F12c/cc-pVQZ-F12, no symmetry, 8 processes per box, 2 threads each) with custom parameters

--tuning-mpplat 1 and --tuning-mppspeed 7000

(i.e., close to the theoretical hardware values)

and am seeing about a 10% speedup in wall clock time, but presumably I am living dangerously here, as the true latency and bandwidth reflect software overheads...

On the same question: what values are optimal for running all inside one box?

Many thanks in advance!
Jan Martin

*** "Computational quantum chemistry and more" ********* rMBP *************************************
Dr. Gershom (Jan M.L.) Martin | Baroness Thatcher Professor of Chemistry
Department of Organic Chemistry
Weizmann Institute of Science | Kimmelman Building, Room 361 | 76100 Rehovot, ISRAEL
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