-lessl

The Engineering and Scientific Subroutine Library (ESSL) is a collection of high performance numerical routines. These routines are very highly optimized for the POWER3 architecture, and using them will almost always produce the fastest possible code for any given numerical algorithm.

If the -lessl argument is specified at link time, single threaded versions of these routines will be used from the ESSL serial library.

-lesslsmp

Some of these subroutines are also available in multithreaded versions that will run in parallel over a node using the shared memory parallel processing programming model. If the -lesslsmp argument is used at link time, these versions will be loaded if they are available, and by default these routines will be run with sixteen user threads. The number of user threads that the routine will use can be controlled by the OMP_NUM_THREADS in the manner described at Changing the number of threads and tasks. The routine will run with sixteen user threads if this variable is not set.