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Re: memory limits and thread stack sizes

Robert Schweikert <Robert dot Schweikert at abaqus dot com> writes:

> Hi all I have a couple of questions with respect to glibc and the kernel
> and the SuSE 7.3, 8.0, and 8.1 and RedHat 8.0 distributions. Hopefully
> someone can shed some light into the darkness that I live in at the
> moment. Both problem apply to x86 boxes.
> Problem 1.)
> An executable created by linking Fortran and C++ code seg faults when
> linked with -lpthread but works when not linked against the thread
> library.
> - this occurs when using the -auto flag when compiling the Fortran code,
> using the Intel Fortran compiler on SuSE 7.3 (glibc 2.2.4) and SuSE 8.0
> (glibc 2.2.5)
> - this works using the -auto flag when compiling the Fortran code, using
> the Intel Fortran compiler on RedHat 8.0

This could  mean that your program uses a too large stack.  Red Hat 8
has glibc 2 and if set up properlay allows a larger stack.

> - this works using the -automatic flag when using g77 for the Fortran
> code on all tested distributions (SuSE 7.3, SuSE 8.0, and RedHat 8.0)

g77 and Intel compiler handle this differently.

> According to Intel there is an issue with threads and the thread
> stacksize limit. However, setting the stack limit to 4 MB (limit
> stacksize 4096) and setting the KMP_STACKSIZE environment variable to 4
> MB did not help. The program that is being executed is very short and
> has a small stack thus that the 4MB limit should be more than
> sufficient.

> The question now is does anyone know what the SuSE folks did when
> compiling glibc and is there a way for me to work around this problem?

SuSE ships a source RPM, so you can look it up yourself.

> Also does anyone know how SuSE 8.1 behaves with respect to this issue?

The same as older releases.  There's a glibc compiled for i686 that
should not have these issues (using floating stacks) but that was
misconfigured unfortunatly :-(

> Problem 2.)
> Allocation of memory past 2GB for 1 process does not appear to work on
> SuSE 7.3 (glibc-2.2.4), not yet tested on RedHat 8.0 and SuSE 8.0. We
> use malloc for pretty much all memory allocation. 

What do you mean with allocation?  malloc (2GB)?  That might be a bug
in glibc.  Do you have a sample test program?  Please report this
using gnats after having verified that it fails indeed with newer
glibc (2.3.x) releases.

> I have tried to find some detailed info on this with respect to
> distributions and versions of glibc and the kernel but what I found was
> either confusing or very old. Help is much appreciated.

 Andreas Jaeger
  SuSE Labs aj at suse dot de
   private aj at arthur dot inka dot de

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