Re: [PATCH v2 1/2] nohz: add tick_nohz_full_clear_cpus() and _set_cpus() APIs

From: Frederic Weisbecker
Date: Mon Apr 06 2015 - 14:29:51 EST


On Mon, Apr 06, 2015 at 02:16:44PM -0400, cmetcalf@xxxxxxxxxx wrote:
> From: Chris Metcalf <cmetcalf@xxxxxxxxxx>
>
> The "clear" API is useful, for example, to modify a cpumask to avoid
> the nohz cores so that interrupts aren't sent to them.
>
> Likewise the "set" API is useful to modify a cpumask indicating some
> special nohz-type functionality so that the nohz cores are
> automatically added to that set.
>
> Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
> ---
> Frederic, if you could ack this patch (and maybe the next) before
> I ask for it to be pulled into the timer tree that would be great.
> I will wait a few days before asking in case anyone else has any
> other issues or would like to provide an Acked-by.

Sure, or better yet I should take them since they are full nohz code.
And I have a pending pile to pull-request to timer tree.

Thanks.

>
> v2: put the "...set_cpus" API together with the change to
> init_sched_domains() so that they can go into the timer tree
> independently of other changes in my tree.
>
> include/linux/tick.h | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/include/linux/tick.h b/include/linux/tick.h
> index 9c085dc12ae9..29456c443970 100644
> --- a/include/linux/tick.h
> +++ b/include/linux/tick.h
> @@ -186,6 +186,18 @@ static inline bool tick_nohz_full_cpu(int cpu)
> return cpumask_test_cpu(cpu, tick_nohz_full_mask);
> }
>
> +static inline void tick_nohz_full_clear_cpus(struct cpumask *mask)
> +{
> + if (tick_nohz_full_enabled())
> + cpumask_andnot(mask, mask, tick_nohz_full_mask);
> +}
> +
> +static inline void tick_nohz_full_set_cpus(struct cpumask *mask)
> +{
> + if (tick_nohz_full_enabled())
> + cpumask_or(mask, mask, tick_nohz_full_mask);
> +}
> +
> extern void __tick_nohz_full_check(void);
> extern void tick_nohz_full_kick(void);
> extern void tick_nohz_full_kick_cpu(int cpu);
> @@ -194,6 +206,8 @@ extern void __tick_nohz_task_switch(struct task_struct *tsk);
> #else
> static inline bool tick_nohz_full_enabled(void) { return false; }
> static inline bool tick_nohz_full_cpu(int cpu) { return false; }
> +static inline void tick_nohz_full_clear_cpus(struct cpumask *mask) { }
> +static inline void tick_nohz_full_set_cpus(struct cpumask *mask) { }
> static inline void __tick_nohz_full_check(void) { }
> static inline void tick_nohz_full_kick_cpu(int cpu) { }
> static inline void tick_nohz_full_kick(void) { }
> --
> 2.1.2
>
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