Messages in this thread | | | Date | Mon, 5 Feb 2024 21:30:02 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH v10 18/20] timers: Implement the hierarchical pull model |
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Le Mon, Feb 05, 2024 at 02:29:34PM +0100, Anna-Maria Behnsen a écrit : > Anna-Maria Behnsen <anna-maria@linutronix.de> writes: > > > Frederic Weisbecker <frederic@kernel.org> writes: > > > >> Le Thu, Feb 01, 2024 at 05:15:37PM +0100, Anna-Maria Behnsen a écrit : > >>> Frederic Weisbecker <frederic@kernel.org> writes: > >>> > >>> > Le Mon, Jan 15, 2024 at 03:37:41PM +0100, Anna-Maria Behnsen a écrit : > >>> > Heh, I was about to say that it's impossible that timer_base_is_idle() > >>> > at this stage but actually if we run in nohz_full... > >>> > > >>> > It happens so that nohz_full is deactivated until rcutree_online_cpu() > >>> > which calls tick_dep_clear() but it's a pure coincidence that might > >>> > disappear one day. So yes, let's keep it that way. > >>> > >>> I instrumented the code (with NOHZ FULL and NOHZ_IDLE) to make sure the > >>> timer migration hierarchy state 'idle' is in sync with the timer base > >>> 'idle'. And this was one part where it was possible that it runs out of > >>> sync as I remember correctly. But if I understood you correctly, this > >>> shouldn't happen at the moment? > >> > >> Well, it's not supposed to :-) > > > > Hmm, let me double check this and run the tests on the instrumented > > version... > > I added a prinkt() to verify what I think I remember. I was able to see > the prints. So it seems, that the coincidence that nohz_full is > deactivated until rcutree_online_cpu() already disappeared.
Nice, then I guess it can become a WARN_ON.
Thanks.
> > --- a/kernel/time/timer_migration.c > +++ b/kernel/time/timer_migration.c > @@ -1672,6 +1672,8 @@ static int tmigr_cpu_online(unsigned int > tmc->idle = timer_base_is_idle(); > if (!tmc->idle) > __tmigr_cpu_activate(tmc); > + else > + printk("TIMER BASE IS IDLE\n"); > tmc->online = true; > raw_spin_unlock_irq(&tmc->lock); > return 0; > > Thanks, > > Anna-Maria >
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