 A typical sampling period is 0.01 second (10 milliseconds) or 0.001 second (1 ms) or in other words 100 or 1000 samples per second of CPU running time.In some versions, such as BSD, profiling of shared libraries can be limited because of restrictions of the profil function, which may be implemented as library function or as system call.There were analogous utility in glibc called 'sprof' to profile dynamic libraries.