<div dir="ltr">A SEGV is definitely a memory access problem, as PETSc suggests, it is likely to be a memory access out of range. <br><br><div>I don't recommend trying to debug this problem on amdahl, can you reproduce the problem just running with multiple processes on your workstation?</div>
<div><br></div><div>Warm Regards,</div><div>Aron</div><div><br><div class="gmail_quote">On Wed, Apr 21, 2010 at 12:34 PM, (Rebecca) Xuefei YUAN <span dir="ltr"><<a href="mailto:xy2102@columbia.edu">xy2102@columbia.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Dear all,<br>
<br>
I checked the code with valgrind, and there is no memory problem, but when running parallelly, there is a message like<br>
<br>
[0]PETSC ERROR: ------------------------------------------------------------------------<br>
[0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation, probably memory access out of range<br>
srun: error: task 0: Exited with exit code 59<br>
[0]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger<br>
[0]PETSC ERROR: or see <a href="http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#Signal[0]PETSC" target="_blank">http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#Signal[0]PETSC</a> ERROR: or try <a href="http://valgrind.org" target="_blank">http://valgrind.org</a> on linux or man libgmalloc on Apple to find memory corruption errors<br>
[0]PETSC ERROR: likely location of problem given in stack below<br>
[0]PETSC ERROR: --------------------- Stack Frames ------------------------------------<br>
[0]PETSC ERROR: Note: The EXACT line numbers in the stack are not available,<br>
[0]PETSC ERROR: INSTEAD the line number of the start of the function<br>
[0]PETSC ERROR: is given.<br>
[0]PETSC ERROR: --------------------- Error Message ------------------------------------<br>
[0]PETSC ERROR: Signal received!<br>
[0]PETSC ERROR: ------------------------------------------------------------------------<br>
[0]PETSC ERROR: Petsc Release Version 3.0.0, Patch 7, Mon Jul 6 11:33:34 CDT 2009<br>
[0]PETSC ERROR: See docs/changes/index.html for recent updates.<br>
[0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.<br>
[0]PETSC ERROR: See docs/index.html for manual pages.<br>
[0]PETSC ERROR: ------------------------------------------------------------------------<br>
[0]PETSC ERROR: /tmp/lustre/home/xy2102/April2110/die0/./twqt2ff.exe on a linux-c-g named sci-m0n0.scsystem by xy2102 Wed Apr 21 05:30:10 2010<br>
[0]PETSC ERROR: Libraries linked from /home/xy2102/soft/petsc-3.0.0-p7/linux-c-gnu-debug/lib<br>
[0]PETSC ERROR: Configure run at Mon Jul 20 13:56:37 2009<br>
[0]PETSC ERROR: Configure options --with-cc=mpicc --with-fc=mpif77 --with-mpiexec=srun --with-debugging=1 --with-fortran-kernels=generic --with-shared=0 --CFLAGS=-G0 --FFLAGS=-G0<br>
[0]PETSC ERROR: ------------------------------------------------------------------------<br>
[0]PETSC ERROR: User provided function() line 0 in unknown directory unknown file<br>
application called MPI_Abort(MPI_COMM_WORLD, 59) - process 0<br>
In: PMI_Abort(59, application called MPI_Abort(MPI_COMM_WORLD, 59) - process 0)<br>
srun: error: task 2-3: Killed<br>
srun: error: task 1: Killed<br>
<br>
What is wrong?<br>
<br>
Cheers,<br>
<br>
Rebecca<br><font color="#888888">
<br>
-- <br>
(Rebecca) Xuefei YUAN<br>
Department of Applied Physics and Applied Mathematics<br>
Columbia University<br>
Tel:917-399-8032<br>
<a href="http://www.columbia.edu/~xy2102" target="_blank">www.columbia.edu/~xy2102</a><br>
<br>
</font></blockquote></div><br></div></div>