Messages in this thread Patch in this message | | | From | Anna-Maria Behnsen <> | Subject | Re: [PATCH v10 18/20] timers: Implement the hierarchical pull model | Date | Mon, 05 Feb 2024 14:29:34 +0100 |
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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.
--- 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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