Subject: Re: Problems with compiling/executing atm program on Sun Workstation
From: Jim Rosinski (rosinski@bearmtn-e0.cgd.ucar.edu)
Date: Wed Jan 13 1999 - 12:20:13 MST
CCM Users;
It seems that many users of the NCAR CCM are encountering "segmentation
fault" problems when running the model or boundary dataset creation codes on
non-Cray platforms. Very often the cause of the problem is that the machine
on which they are running does not provide an adequate default stack memory
limit. A first-try remedy to this problem is to put "limit stacksize
unlimited" into the user's .cshrc file. I don't know how to do the
equivalent thing under shells which are not tcsh or csh.
There are 2 stack memory limits involved. The above solution only addresses
the "soft limit", which sets the max allowed stack size to the "hard limit".
This value may or may not be sufficient to address the problem, as the hard
limit is a boot-time parameter which will differ from machine to machine.
You must have root access to change its value. Yesterday I sent a message
explaining how to do this on Linux machines. I do not know how to change
the hard limit under other operating systems.
If all the above changes continue to result in seg fault problems, another
thing to try is to make the default memory allocation for local variables
static rather than stack-based at the application level. Using SUN's f77
compiler for example, this is accomplished by deleting "-stackvar" from
FFLAGS in the Makefile. Be aware however, that disabling stack memory
allocation in this way means that shared memory multitasking MUST also be
disabled or incorrect answers will result. The current CCM distribution only
supports shared memory multitasking on SGI and Cray machines, and only for
the GCM itself. All ancillary codes are single-tasked. (i.e. you only have
to worry if you are running CCM3 on an SGI. In this case, you must get rid
of "-mp" from FFLAGS and LDFLAGS).
Regards,
Jim Rosinski
CCM Core Group
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