2013/10/2 Daniel Lezcano <daniel.lezc...@linaro.org>: > The sleep_length is computed in the tick_nohz_stop_sched_tick function but it > is used later in the code with in between the local irq enabled. > > cpu_idle_loop > tick_nohz_idle_enter [ exits with local irq enabled ] > __tick_nohz_idle_enter > tick_nohz_stop_sched_tick > ... > > arch_cpu_idle > menu_select [ uses here 'sleep_length' ] > ... > > Between the computation of the sleep length and its usage, some interrupts > may occur, making the sleep length shorter than actually it is because of the > interrupt processing
So, do you mean that the ts->sleep_length would return a value that is too long given that the CPU already spent some time to service the irqs since we computed the sleep length in tick_nohz_idle_enter()? But then tick_nohz_irq_exit() should take care of that as it calls again tick_nohz_stop_sched_tick(). So I'm a bit confused. > or different if the timer itself expired. Same here, if the timer expired, it triggers an interrupt which can do two things: 1) reprogram a new timer and this recompute sleep_length 2) set_need_resched() and then exit the idle loop, so arch_cpu_idle() won't even be called. Or the timer interrupts hlt, but then menu_select() was called before. So I probably missed something here. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
