[MITgcm-support] speed up!

[Van Thinh Nguyen]

Hi,

I am using mitgcm to simulate internal solitary waves generated by tidal 
forcing over a topography. So I need to run the model with options: 
non-hydrostatic & free surface, and OBCs package.
Everything is doing well with lower resolution, however the computational 
time is a big concern when I would like to increase the resolution to see 
the solitary waves.
I currently used a resolution of 4000*500*60, running on Altix 
Itanium2 (with 128 cpus x 1.60 GHz), using 32 cpus. To run for 0.1 tidal period T
(4464 s), I need 5 days (time step dt=2s).

I did check the memory when the job runs is:

VIRT = 161 GB (swap + res)
RES  = 2.3 GB (code + data)

I also saw the job state is running about 60 s with 100% CPU then start to 
delay about 40s (maybe due to communication between threads, read/write).

Maybe my chkptFreq (=1.) is set to low?

-----
  pChkptFreq=4464.,
  chkptFreq=1.,
  dumpFreq=2232.0,
  monitorFreq=558,
-----

Any idea to help me to speedup my run? (switch off some parameters, which 
is not neccessary in my case? shall i increase chkptFreq?, ....)


Thanks so much.

Van Thinh


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