[MITgcm-devel] help with debugging flags during compilation

[Jean-Michel Campin]

Hi An,

I am not sure I understand correctly:
Trying to use the simplest CFLAGS, FFLAGS, FOPTIM setting might not be 
the best to compile and run. 
For instance, without:
 -convert big_endian -assume byterecl
it will not be abble to read any "big-endian" binary, which could be a problem.
Or without:
 -mcmodel=medium
it might not run if the memory footprint is too large.

I found that, generally, once I load the right module and set env.variable: 
MPI_INC_DIR to correct location,
I can use one of the 3 "standard" optfile:
 linux_amd64_gfortran
 linux_amd64_ifort11
 linux_amd64_ifort+impi
and it just works.
And the improvement that I would get by fine tuning of some of the compiler 
options is not very significant (and in my case, not worth spending too much time).

And the nice thing about these ones is that you could use "-ieee" or "-devel"
genmake2 option to turn off all optimisation level (-ieee) or even turn on
all debug option (-devel).

Now in your case, are you running with debugMode=.TRUE., in eedata ?

Cheers,
Jean-Michel

On Tue, Feb 27, 2018 at 04:24:04PM -0500, An Nguyen wrote:
> Hello mitgcm gurus,
> 
> For the last 2 years I've been having problem with the mitgcm crashing right out of the gate without producing any STDOUT or STDERR or any message at all on the various computing nodes we have at UT Austin, and the only help tech-support can provide us so far is a message saying that we need to do our own debugging.   
> 
> I'd like to ask for some help with the flags needed to remove all optimization options when compiling the mitgcm (with ifort) in order to enter debug mode such as dbg or this ddt tool they suggested (https://portal.tacc.utexas.edu/software/ddt <https://portal.tacc.utexas.edu/software/ddt>) .  The genmake2 various flags are very elaborate with various options for CFLAGS, FFLAGS, FOPTIM that are really beyond my comprehension (I spent 5 hours last night fiddling around and didn't succeed), so I'm hoping to get some suggestions on what I need to set: would stripping ALL CFLAGS and FFLAGS and FOPTIM and only use 
> 
> FFLAGS='-g'
> FOPTIM='-O0'
> CFLAGS=''
> 
> an option?  Any suggestion, including a sampled very-stripped-down optfile would be very helpful for me.  I can provide more information (within my comprehension) if needed.
> 
> Many thanks,
> An
> 
> An T Nguyen, Ph.D. 
> Institute of Computational Engineering and Sciences 
> The University of Texas at Austin, 
> 201 East 24th Street, POB 4.234, 
> Austin, TX 78712, USA 
> Phone: (512) 471-4207 
> <atnguyen at ices.utexas.edu>
> 

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