You can check to see if your program is running in parallel, i.e. it is using more than 1 thread by typing the following command:
ps -Lu username -o pid,gid,lwp,psr,s,comm
where username is your login.
This will give a table of your currently active processes and their lightweight threads. If your program is running in parallel then multiple instances of it should exist that have 0 as their status, i.e. they are running on a processor. For example, below the serial version of swim has only 1 thread. The parallel version always has multiple threads, however when running on p processors only p threads have a 0 status. The PSR column should generally be -, however if the lwps are bound to a processor it will appear here.
peta.ecn.purdue.edu 140: ps -Lu mjvoss -o pid,gid,lwp,psr,s,comm PID GID LWP PSR S COMMAND 1135 1 1 - S -tcsh 29884 1 1 - S -tcsh 2242 1 1 - O swim_serial 29611 1 1 - S emacs (a) A Serial Version of Swim peta.ecn.purdue.edu 141: ps -Lu mjvoss -o pid,gid,lwp,psr,s,comm PID GID LWP PSR S COMMAND 1135 1 1 - S -tcsh 29884 1 1 - S -tcsh 2250 1 1 - O swim_parallel_on_1 2250 1 2 - S swim_parallel_on_1 2250 1 3 - S swim_parallel_on_1 2250 1 4 - S swim_parallel_on_1 2250 1 5 - S swim_parallel_on_1 29611 1 1 - S emacs (b) A Parallel Version of swim running on 1 processor peta.ecn.purdue.edu 146: ps -Lu mjvoss -o pid,gid,lwp,psr,s,comm PID GID LWP PSR S COMMAND 1135 1 1 - S -tcsh 29884 1 1 - S -tcsh 2257 1 1 - O swim_parallel_on_2 2257 1 2 - S swim_parallel_on_2 2257 1 3 - S swim_parallel_on_2 2257 1 4 - S swim_parallel_on_2 2257 1 5 - S swim_parallel_on_2 2257 1 6 - O swim_parallel_on_2 2257 1 7 - S swim_parallel_on_2 29611 1 1 - S emacs (c) A Parallel Version of Swim running on 2 processors