In Solaris releases prior to 2.6, calling profil() in a multithreaded program would impact only the calling LWP; the profile state was not inherited at LWP creation time. To profile a multithreaded program with a global profile buffer, each thread needed to issue a call to profil() at threads start-up time, and each thread had to be a bound thread. This was cumbersome and did not easily support dynamically turning profiling on and off. In Solaris 2.6 and later releases, the profil() system call for multithreaded processes has global impact—that is, a call to profil() impacts all LWPs/threads in a process. This may cause applications that depend on the previous per-LWP semantic to break, but it is expected to improve multithreaded programs that wish to turn profiling on and off dynamically at runtime.