linux-kernel - Re: [PATCH v3 2/6] hrtimer: Add support for deferrable timer into the hrtimer

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Date:	Thu, 20 Feb 2014 10:49:46 -0800
From:	John Stultz <john.stultz@...aro.org>
To:	Alexey Perevalov <a.perevalov@...sung.com>,
	linux-kernel@...r.kernel.org, tglx@...utronix.de
CC:	anton@...sg.org, kyungmin.park@...sung.com, cw00.choi@...sung.com,
	akpm@...ux-foundation.org
Subject: Re: [PATCH v3 2/6] hrtimer: Add support for deferrable timer into
 the hrtimer

On 02/20/2014 12:40 AM, Alexey Perevalov wrote:
> From: Thomas Gleixner <tglx@...utronix.de>
>
> This patch introduces new public CLOCKID constants for
> user space API, such as timerfd. It extends hrtimer API and makes
> possible to have unified interfaces where deferreble functionality is
> used. In-kernel users such as device drivers could find benefits too.
>
> High resolution timer now could work with CLOCK_REALTIME_DEFERRABLE,
> CLOCK_MONOTONIC_DEFERRABLE, CLOCK_BOOTTIME_DEFERRABLE.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Alexey Perevalov <a.perevalov@...sung.com>
> ---
>  include/linux/hrtimer.h   |    3 +++
>  include/uapi/linux/time.h |    3 +++
>  kernel/hrtimer.c          |   62 +++++++++++++++++++++++++++++++++++----------
>  3 files changed, 55 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
> index d19a5c2..fe1159c 100644
> --- a/include/linux/hrtimer.h
> +++ b/include/linux/hrtimer.h
> @@ -158,6 +158,9 @@ enum  hrtimer_base_type {
>  	HRTIMER_BASE_REALTIME,
>  	HRTIMER_BASE_BOOTTIME,
>  	HRTIMER_BASE_TAI,
> +	HRTIMER_BASE_MONOTONIC_DEFERRABLE,
> +	HRTIMER_BASE_REALTIME_DEFERRABLE,
> +	HRTIMER_BASE_BOOTTIME_DEFERRABLE,
>  	HRTIMER_MAX_CLOCK_BASES,
>  };
>  
> diff --git a/include/uapi/linux/time.h b/include/uapi/linux/time.h
> index e75e1b6..bb8dc60 100644
> --- a/include/uapi/linux/time.h
> +++ b/include/uapi/linux/time.h
> @@ -56,6 +56,9 @@ struct itimerval {
>  #define CLOCK_BOOTTIME_ALARM		9
>  #define CLOCK_SGI_CYCLE			10	/* Hardware specific */
>  #define CLOCK_TAI			11
> +#define CLOCK_REALTIME_DEFERRABLE	12
> +#define CLOCK_MONOTONIC_DEFERRABLE	13
> +#define CLOCK_BOOTTIME_DEFERRABLE	14

Adding the deferrable HRTIMER bases above is right, but I don't think we
agreed on adding the _DEFERRABLE clockids.

I'd instead prefer you use add a new TIMER_DEFERABLE flags argument, and
use the combination of the clockid + flag to decide which HRTIMER base
is used.

thanks
-john

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