linux-kernel - Re: [PATCH v2 1/2] nohz: add tick_nohz_full_clear_cpus() and _set

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Message-ID: <20150406182934.GA852@lerouge>
Date:	Mon, 6 Apr 2015 20:29:37 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	cmetcalf@...hip.com
Cc:	"Peter Zijlstra (Intel)" <peterz@...radead.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] nohz: add tick_nohz_full_clear_cpus() and
 _set_cpus() APIs

On Mon, Apr 06, 2015 at 02:16:44PM -0400, cmetcalf@...hip.com wrote:
> From: Chris Metcalf <cmetcalf@...hip.com>
> 
> 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@...hip.com>
> ---
> 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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