On the KNL, what is a bus error (signal 7) as distinguished from a seg fault (11)? I am getting these with (very) low probability in OpenMP regions of my Fortran code. The same code has worked fine for years on mira. Also on KNL the same subroutines have been successfully invoked up to 100,000 times. But attempts to scale up to bigger runs are being hit now. Removing the !$OMP statements for the given loop seems to get rid of the bus error, but of course this slows the program down -- we have to be able to use multithreading on this machine. Steve -- Steven C. Pieper, Senior Physicist Emeritus: [email protected] Argonne National Laboratory, Physics Division, Bldg. 203, Argonne, IL 60439 Phone: 630-252-4232 Fax -6008 Secretary, Debra Beres, -4100 http://www.phy.anl.gov/theory/staff/scp.html