All timers are per-process except for the real time profile interval timer, which is per_LWP. See the setitimer(2) man page for a description of the ITIMER_REALPROF timer.
The timer IDs of per-process timers are usable from any LWP. The expiration signals are generated for the process rather than directed to a specific LWP.
The per-process timers are deleted only by timer_delete(3RT), or when the process terminates.
In the Oracle Solaris 11.1 release, the POSIX timer API has been enhanced to provide a thread (LWP) directed signal. The thread directed signal notification can be requested with the use of the SIGEV_SIGNAL_THR sigevent type. You can effectively create per thread timers by using this sigevent type. See the timer_create (3C) man page for more information.