Opened 18 months ago

Closed 7 months ago

#2214 closed Enhancement (fixed)

minimize jpj for the domains of the last row

Reported by: smasson Owned by: systeam
Priority: low Milestone:
Component: LBC Version: trunk
Severity: minor Keywords:
Cc: Review:
MP ready?:
Progress:

Description

Context

Even with the last optimizations, the north pole folding has still an extra coast that creates unbalance. This reduces the limit at which you can push the scalability of the model…

However from version 4, jpj is no more constrained to be the same for each mpi subdomains.
We can therefore try to minimize the size of jpj for the mpi subdomains located on the last row. They will compute less and this could help us to compensate for the extra coast of the north pole folding

Proposal

When jperio == 3, 4 .OR. jperio == 5, 6 :

  • do the NP folding after the east-west communications but before the south-north communication because if we keep the NP folding after the south-north communication, the south communication will force a synchronization of the last row with its southern neighbors and we would loose all the benefit of computing faster!
  • minimize jpj for the last row. As the NP folding will be done before the south communication, the size of jpj should be at least 5 for jperio = 4 (as V and F folding involves line jpj-3 that should not be the southern boundary) and 4 for jperio = 6 (as V and F folding involves line jpj-2 that should not be the southern boundary)

Commit History (1)

ChangesetAuthorTimeChangeLog
10542smasson2019-01-17T16:57:40+01:00

trunk: improve NP folding balance, see #2214

Change History (2)

comment:1 Changed 18 months ago by smasson

In 10542:

trunk: improve NP folding balance, see #2214

comment:2 Changed 7 months ago by smasson

  • Resolution set to fixed
  • Status changed from new to closed
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