linux-kernel - Re: [PATCH] clocksource: arch_timer: Set dynamic irq affinity on mmio clockevent

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Date:	Tue, 14 Jan 2014 09:40:10 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Stephen Boyd <sboyd@...eaurora.org>
CC:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] clocksource: arch_timer: Set dynamic irq affinity on
 mmio clockevent

On 01/06/2014 11:56 PM, Stephen Boyd wrote:
> Set the CLOCK_EVT_FEAT_DYNIRQ flag on the memory mapped
> clockevent so that we save power by waking up the CPU with the
> next event when this timer is used in broadcast mode.
>
> Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
> ---
>   drivers/clocksource/arm_arch_timer.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 95fb944e15ee..57e823c44d2a 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -277,6 +277,7 @@ static void __arch_timer_setup(unsigned type,
>   			clk->set_next_event = arch_timer_set_next_event_phys;
>   		}
>   	} else {
> +		clk->features |= CLOCK_EVT_FEAT_DYNIRQ;
>   		clk->name = "arch_mem_timer";
>   		clk->rating = 400;
>   		clk->cpumask = cpu_all_mask;
>

Applied in my tree for 3.15.

I am curious how much you saved in your current scenario. Did you had 
time to do some rough measurements ?

Thanks
   -- Daniel



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