mani bhatti wrote: > Thanks Jan for your reply > Actually the semaphore and mutexes stuff you have referred to i have > already grounds for them.The only problem i have is please some body > tell me that i dont want to make a thread periodic i,e i dont want to > call a thread after periodic time interval i wanted it to make it > aperiodic like threads in C++ are scheduled by scheduler byitself This has nothing to do with C++, rather with the class library you are used to. > and sleep on waiting condition with out any specific time interval > and wake only when signalled from pariodic thread. I hope you > understand my point.Thanks a lot . Let's try it differently: thread_a() { rt_task_set_periodic(...); while (1) { rt_task_wait_period(NULL); /* do some work */ if (I_should_trigger_thread_b) rt_sem_v(&sem); } } thread_b() { while (1) { rt_sem_p(&sem, TM_INFINITE); /* so some other work */ } } Again, read up what the services are exactly doing or you will be lost once you have to modify things only slightly. Jan