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From: Anna-Maria Behnsen <anna-maria@linutronix.de>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>
Subject: Re: [PATCH 4/9] timers: Always keep track of next expiry
Date: Tue, 14 Jul 2020 10:49:28 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.2007141037490.1386@somnus> (raw)
In-Reply-To: <20200707013253.26770-5-frederic@kernel.org>

Hi Frederic,

On Tue, 7 Jul 2020, Frederic Weisbecker wrote:

> So far next expiry was only tracked while the CPU was in nohz_idle mode
> in order to cope with missing ticks that can't increment the base->clk
> periodically anymore.
> 
> We are going to expand that logic beyond nohz in order to spare timers
> softirqs so do it unconditionally.
> 
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
> Cc: Juri Lelli <juri.lelli@redhat.com>
> ---
>  kernel/time/timer.c | 36 +++++++++++++++++++-----------------
>  1 file changed, 19 insertions(+), 17 deletions(-)
> 
> diff --git a/kernel/time/timer.c b/kernel/time/timer.c
> index acf7cb8c09f8..8a4138e47aa4 100644
> --- a/kernel/time/timer.c
> +++ b/kernel/time/timer.c
> @@ -558,8 +558,22 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer)
>  	 * 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 the base lock:
>  	 */
> -	if (!base->is_idle)
> -		return;
> +	if (base->is_idle)
> +		wake_up_nohz_cpu(base->cpu);
> +}
> +
> +/*
> + * Enqueue the timer into the hash bucket, mark it pending in
> + * the bitmap and store the index in the timer flags.
> + */
> +static void enqueue_timer(struct timer_base *base, struct timer_list *timer,
> +			  unsigned int idx)
> +{
> +	hlist_add_head(&timer->entry, base->vectors + idx);
> +	__set_bit(idx, base->pending_map);
> +	timer_set_idx(timer, idx);
> +
> +	trace_timer_start(timer, timer->expires, timer->flags);
>  
>  	/* Check whether this is the new first expiring timer: */
>  	if (time_after_eq(timer->expires, base->next_expiry))
> @@ -578,21 +592,7 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer)
>  	} else {
>  		base->next_expiry = timer->expires;
>  	}
> -	wake_up_nohz_cpu(base->cpu);
> -}
>  
> -/*
> - * Enqueue the timer into the hash bucket, mark it pending in
> - * the bitmap and store the index in the timer flags.
> - */
> -static void enqueue_timer(struct timer_base *base, struct timer_list *timer,
> -			  unsigned int idx)
> -{
> -	hlist_add_head(&timer->entry, base->vectors + idx);
> -	__set_bit(idx, base->pending_map);
> -	timer_set_idx(timer, idx);
> -
> -	trace_timer_start(timer, timer->expires, timer->flags);
>  	trigger_dyntick_cpu(base, timer);
>  }
>  

Could you please split those two hunks which do only a restructuring into a
separate patch?

Thanks,

	Anna-Maria


  reply	other threads:[~2020-07-14  8:49 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-07  1:32 [PATCH 0/9] timer: Reduce timers softirq v2 Frederic Weisbecker
2020-07-07  1:32 ` [PATCH 1/9] timer: Move trigger_dyntick_cpu() to enqueue_timer() Frederic Weisbecker
2020-07-09 12:17   ` Anna-Maria Behnsen
2020-07-15 13:20     ` Frederic Weisbecker
2020-07-07  1:32 ` [PATCH 2/9] timer: Add comments about calc_index() ceiling work Frederic Weisbecker
2020-07-14  9:13   ` Thomas Gleixner
2020-07-17 12:55     ` Frederic Weisbecker
2020-07-07  1:32 ` [PATCH 3/9] timer: Optimize _next_timer_interrupt() level iteration Frederic Weisbecker
2020-07-07  1:32 ` [PATCH 4/9] timers: Always keep track of next expiry Frederic Weisbecker
2020-07-14  8:49   ` Anna-Maria Behnsen [this message]
2020-07-17 12:51     ` Frederic Weisbecker
2020-07-07  1:32 ` [PATCH 5/9] timer: Reuse next expiry cache after nohz exit Frederic Weisbecker
2020-07-07  1:32 ` [PATCH 6/9] timer: Expand clk forward logic beyond nohz Frederic Weisbecker
2020-07-07  1:32 ` [PATCH 7/9] timer: Spare timer softirq until next expiry Frederic Weisbecker
2020-07-07  1:32 ` [PATCH 8/9] timer: Remove must_forward_clk Frederic Weisbecker
2020-07-07  1:32 ` [PATCH 9/9] timer: Lower base clock forwarding threshold Frederic Weisbecker
2020-07-09  7:02 ` [PATCH 0/9] timer: Reduce timers softirq v2 Juri Lelli

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