I found some difficulties in realtime posix timer.

there are two thread in my program. all of them set realtime sched.
one is timer thread. set prioir 1, which is highest. create posix timer ,using timer_create.
the other is main task.set prioir 99, which is lowest.

the period of timer is 1ms. when cpu is not busy, everything OK. when cpu get more task. timer go bad. i mean timer handle can't process in time.

i use 2.6 kernel with realtime patch.
could you give help?