Wolfgang Grandegger wrote: > -bash-3.2# cat stat sched > CPU PID MSW CSW PF STAT %CPU NAME > 0 0 0 12563 0 00500080 99.9 ROOT > 0 1407 1 1 0 00300380 0.0 cancel-test > 0 1409 1 3 1 00300380 0.0 ctrl_func > 0 1410 1 3 0 00300380 0.0 calc_func > 0 0 0 4373414 0 00000000 0.1 IRQ512: [timer] > CPU PID PRI PERIOD TIMEOUT TIMEBASE STAT NAME > 0 0 39 0 0 master R ROOT > 0 1407 0 0 0 master X cancel-test > 0 1409 39 0 0 master X ctrl_func > 0 1410 38 0 0 master X calc_func > > When does this priority coupling happen.
Each time a thread switches from primary to secondary mode, it is enqueued by decreasing priority order into a list tracking relaxed threads for the given CPU. The root thread for that CPU dynamically inherits the priority of the topmost thread queued to the relax/RPI list. This list is updated as soon as: - a primary mode thread is relaxed (enqueued) - a relaxed thread goes back to primary mode (dequeued) - a relaxed thread blocks on a linux service (dequeued) - a relaxed thread resumes from a linux service (enqueued) When no more threads are linked to the RPI list, the root thread priority is downgraded to -1. In effect, this couples the Xenomai priority scale to the linux one, so that switching to secondary mode does not allow lower priority threads still in primary mode to preempt. CONFIG_XENO_OPT_PRIOCPL controls whether such coupling should happen at all. -- Philippe. _______________________________________________ Xenomai-help mailing list Xenomai-help@gna.org https://mail.gna.org/listinfo/xenomai-help
