On 5/20/2014 1:18 AM, Sebastian Huber wrote: > On 2014-05-20 01:39, Joel Sherrill wrote: >> Hi >> >> I have set affinity and unblock logic in place and am testing scenarios. >> I still have to work on blocking. >> >> I am playing with a scenario now that changes the affinity of a thread >> that is executing. I am concerned that changing the affinity of a thread >> that is executing may have a window to address similar to restart of >> self. You are still executing on the core but could be moved as part of >> setting affinity. >> >> Before the set affinity of smp1 to core 1 is executed, the set of the >> tasks >> >> EXECUTING / HEIR / SWITCH NEEDED >> CPU 0: 0x0a010004 @ 5 / 0x0a010004 @ 5 false (smp4) >> CPU 1: 0x0a010003 @ 6 / 0x0a010003 @ 6 false (smp3) >> CPU 2: 0x0a010002 @ 6 / 0x0a010002 @ 6 false (smp2) >> CPU 3: 0x0a010001 @ 5 / 0x0a010001 @ 5 false (smp1) >> >> When set affinity internally sets the state of smp1 to STATES_MIGRATE, >> the heir on cpu 3 is changed to smp5. >> >> The affinity is updated and when STATES_MIGRATE is cleared, smp1 is >> declared heir on cpu 2. >> >> It is still executing on cpu 3 when it is declared heir on cpu 2. >> >> Wouldn't changing the scheduler for the executing thread have >> a similar issue? You need to finish up the thread with one scheduler >> before moving it. > This is not a problem since this commit: > > http://git.rtems.org/rtems/commit/?id=38b59a6d3052654e356ae16b4a243c362312acce > > See also > > http://git.rtems.org/rtems/tree/testsuites/smptests/smpmigration02/init.c > > The key point is that the is executing indicator moved to the thread context > and the low-level context switch is responsible for it. There exists a point > in time on which a processor executes no context during a context switch. Great! I just worried about a window. Better to ask than debug. :) >> What happens if you end up with a combination of these >> actions at the same time? restart, scheduler change, affinity change. > Currently a scheduler change must not be issued in interrupt context. Apart > from this everything works fine even if you restart a thread during a > scheduler > change since thread dispatching is disabled. > You asked earlier. I think changing affinity should work find from an ISR. It is just set state/clear state.
-- Joel Sherrill, Ph.D. Director of Research & Development joel.sherr...@oarcorp.com On-Line Applications Research Ask me about RTEMS: a free RTOS Huntsville AL 35805 Support Available (256) 722-9985 _______________________________________________ rtems-devel mailing list rtems-devel@rtems.org http://www.rtems.org/mailman/listinfo/rtems-devel
