Opened 3 years ago

Closed 3 years ago

#1962 closed help (answered)

Running LEM on more than 1 processor

Reported by: harveynj Owned by: willie
Component: Large Eddy Model Keywords:
Cc: Platform: ARCHER
UM Version:

Description

Hi,
I have the LEM running on ARCHER but ideally I would like to run it on more than 1 processor.

Do you know if anyone has run it on multiple processors before?

When I try this I get the following error (which seems to suggest that you can't!):
ERROR: This model is meant for only one processor. GC_INIT should never have been accessed

The job files can be found here:
/home/n02/n02/harveynj/work/LEM_runs/r36

Thanks,

Natalie

Change History (7)

comment:1 Changed 3 years ago by willie

Hi Natalie,

Are you using the archer branch or the self_sp branch? The archer branch has test cases 1,2,3 which use NPES=24. I think they worked.

Willie

comment:2 Changed 3 years ago by harveynj

Hi Willie,

Yes, I am using the archer branch. Test case 1 has run for a few output times over the weekend (I have killed it now as just wanted to test the parallel bit). Now I just need to figure out what is different in my job!

Thanks,

Natalie

comment:3 Changed 3 years ago by willie

  • Owner changed from um_support to willie
  • Status changed from new to accepted

Hi Natalie,

Great. I've just upgraded the archer branch to bring it into line with the current archer, so it uses a modern compiler and uses the queues better.

Willie

comment:4 Changed 3 years ago by harveynj

Hi Willie,

As a test I have tried running test case 4 on more than 1 processor by setting NPES=24 and DIIP=48 in the input file. This also gives the error from above "ERROR: This model is meant for only one processor. GC_INIT should never have been accessed". The files for this job are here:
/home/n02/n02/harveynj/work/LEM_runs/r403/

I have been looking into why this might be happening and it looks like it is to do with line 2 in /home/n02/n02/harveynj/work/LEM_runs/r403/BASE/les.f
In r403 this is: ! No GCOM include file for portable model RMDCOS.7529
but in test1 this line reads: Use gcom_mod RMDCOS.6764

(test 1 files can be found here: /home/n02/n02/harveynj/work/LEM_runs/r700/)

I am guessing this difference is just down to a flag being set correctly in the compile script but can't seem to track it down. Do you have any ideas what I might be missing?

Thanks,

Natalie

comment:5 Changed 3 years ago by willie

Hi Natalie,

Test case 4 is a 2D simulation, whereas test case 1 is 3D. The user guide section 4.4.2 specifies IIP=1 for 2D simulations. The LEM code is built, differently for each test case, via nupdate, which uses the UPDATES/define.txt file:

*DEFINE A01_3A,A02_3A,A70_1A,ESRAD
*DEFINE PORT
*DEFINE NOGCOM

so that is why GCOM is not selected.

Willie

comment:6 Changed 3 years ago by harveynj

Hi Willie,

Thanks for that - probably the only place I hadn't looked!

Natalie

comment:7 Changed 3 years ago by ros

  • Resolution set to answered
  • Status changed from accepted to closed
  • UM Version <select version> deleted

Natalie has now got this working so closing this ticket.

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