[FLASH-USERS] Flash4b hangs on BlueGene/Q system

[Mirko Cestari]

Dear users,
we are experiencing some issues in trying to run Flash4b on
our BGQ system if compiled with native xl compilers.
We didn't experience any problem on our previous
BG/P system (we compiled and run successfully the same code/input).

The programs seems to hang indefinitely at the very beginning of
the simulation run. Checking with a debugging tool (totalview) the stack
trace turns out to be

Stack Trace
C    __mcount_internal,     FP=19ffffb980
     ._mcount,              FP=19ffffba00
f90  flash,                 FP=19ffffbaa0
     .generic_start_main,   FP=19ffffbd80
C    __libc_start_main,     FP=19ffffbe40

the execution stops at

  =>  program Flash

in Flash.F90, more precisely, the execution runs in an infinite (while) loop
in the function  __mcount_internal in mcount.c

 =>            while (atomic_compare_and_exchange_bool_acq (&p->mcount_hwthd, hwthd, -1));

which to my understanding is a profiling function (please note
no profiling flags have been used to compile the program, is there
any profiling embedded in the code?).

Compiling with gcc gives worse performance but no "freezing" problems.

Have you ran into similar problems on BG/Q systems? Can you point
me to someone that might have encountered the same problem?  

Thanks in advance,
Mirko

--
Mirko Cestari, PhD
m.cestari at cineca.it
CINECA - SuperComputing Applications and Innovation Department - SCAI
via Magnanelli, 6/3 40033 Casalecchio di Reno (Bologna) - ITALY
www.cineca.it