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Groups > linux.kernel > #1420986
| From | Richard Cochran <richardcochran@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [patch 18/20] timer: Forward wheel clock whenever possible |
| Date | 2016-06-13 17:20 +0200 |
| Message-ID | <rJBOG-82T-33@gated-at.bofh.it> (permalink) |
| References | <rJvJf-3OU-5@gated-at.bofh.it> <rJvJg-3OU-61@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Thomas,
On Mon, Jun 13, 2016 at 08:41:04AM -0000, Thomas Gleixner wrote:
> @@ -498,23 +500,27 @@ static void internal_add_timer(struct ti
> __internal_add_timer(base, timer);
>
> /*
> - * Check whether the other CPU is in dynticks mode and needs
> - * to be triggered to reevaluate the timer wheel. We are
> - * protected against the other CPU fiddling with the timer by
> - * holding the timer base lock. This also makes sure that a
> - * CPU on the way to stop its tick can not evaluate the timer
> - * wheel.
> - *
> - * Spare the IPI for deferrable timers on idle targets though.
> - * The next busy ticks will take care of it. Except full dynticks
> - * require special care against races with idle_cpu(), lets deal
> - * with that later.
> - */
> - if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && base->nohz_active) {
> - if (!(timer->flags & TIMER_DEFERRABLE) ||
> - tick_nohz_full_cpu(base->cpu))
> - wake_up_nohz_cpu(base->cpu);
> - }
> + * We might have to IPI the remote CPU if the base is idle and the
> + * timer is not deferrable. If the other cpu is on the way to idle
> + * then it can't set base->is_idle as we hold base lock.
> + */
> + if (!IS_ENABLED(CONFIG_NO_HZ_COMMON) || !base->is_idle ||
> + (timer->flags & TIMER_DEFERRABLE))
> + return;
The tests for is_idle and TIMER_DEFERRABLE are actually checking the
same thing. I was looking at the usage of base.is_idle, and it is
only ever set for BASE_STD.
So the TIMER_DEFERRABLE test is redundant, but maybe this is on
purpose? Anyhow, it did leave me scratching my head.
Thanks,
Richard
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[patch 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
[patch 11/20] hlist: Add hlist_is_last_node() helper Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
Re: [patch 11/20] hlist: Add hlist_is_last_node() helper Paolo Bonzini <pbonzini@redhat.com> - 2016-06-13 12:30 +0200
[patch 07/20] drivers/tty/mips_ejtag: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
[patch 01/20] timer: Make pinned a timer property Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
[patch 17/20] tick/sched: Remove pointless empty function Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
[patch 05/20] driver/net/ethernet/tile: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
[patch 15/20] timer: Move __run_timers() function Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
[patch 12/20] timer: Give a few structs and members proper names Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
[patch 04/20] cpufreq/powernv: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
Re: [patch 04/20] cpufreq/powernv: Initialize timer as pinned Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-13 15:20 +0200
[patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Peter Zijlstra <peterz@infradead.org> - 2016-06-13 13:50 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 14:40 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Eric Dumazet <edumazet@google.com> - 2016-06-13 14:50 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 16:40 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Ingo Molnar <mingo@kernel.org> - 2016-06-14 12:20 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-14 18:40 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-14 19:20 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-14 20:10 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Peter Zijlstra <peterz@infradead.org> - 2016-06-14 22:40 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Peter Zijlstra <peterz@infradead.org> - 2016-06-14 22:50 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Eric Dumazet <edumazet@google.com> - 2016-06-14 23:20 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-15 17:00 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-15 17:00 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-15 18:50 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-16 17:50 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-16 18:10 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Peter Zijlstra <peterz@infradead.org> - 2016-06-16 20:20 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-17 02:50 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-17 06:10 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-16 18:10 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-16 18:20 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Eric Dumazet <edumazet@google.com> - 2016-06-15 17:10 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Richard Cochran <richardcochran@gmail.com> - 2016-06-13 16:40 +0200
Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 16:50 +0200
[patch 14/20] timer: Remove slack leftovers Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
[patch 18/20] timer: Forward wheel clock whenever possible Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
Re: [patch 18/20] timer: Forward wheel clock whenever possible Richard Cochran <richardcochran@gmail.com> - 2016-06-13 17:20 +0200
Re: [patch 18/20] timer: Forward wheel clock whenever possible Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 17:30 +0200
[patch 06/20] drivers/tty/metag_da: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 11:00 +0200
Re: [patch 06/20] drivers/tty/metag_da: Initialize timer as pinned Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-13 15:20 +0200
[patch 03/20] x86/mce: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 11:00 +0200
[patch 08/20] net/ipv4/inet: Initialize timers as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 11:00 +0200
[patch 02/20] x86/apic/uv: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 11:00 +0200
Re: [patch 00/20] timer: Refactor the timer wheel Eric Dumazet <edumazet@google.com> - 2016-06-13 16:20 +0200
Re: [patch 00/20] timer: Refactor the timer wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-13 18:20 +0200
Re: [patch 00/20] timer: Refactor the timer wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-15 17:20 +0200
Re: [patch 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-15 19:10 +0200
Re: [patch 00/20] timer: Refactor the timer wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-15 22:30 +0200
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