I use oprofile version 0.3.
If I set uid root for op_start and op_stop only,
then oprof_start complains that it failed to run op_start,
and that one must be root.
In addition, oprof_start does not seem to recognize if the
profiler is already running.
If I set uid root for oprof_start, too, then everything seems
to work fine.
The problem with setting uid root for oprof_start is that I
then have to 'xhost +'.
And it does not seem logical to me, that one shuold
really need the SUID bit for oprof_start.