linux-kernel - Re: [PATCH v3 5/6] timerfd: Add support for deferrable timers

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Message-ID: <alpine.DEB.2.02.1402201152440.4468@ionos.tec.linutronix.de>
Date:	Thu, 20 Feb 2014 12:09:43 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Alexey Perevalov <a.perevalov@...sung.com>
cc:	linux-kernel@...r.kernel.org, john.stultz@...aro.org,
	Anton Vorontsov <anton@...msg.org>, anton@...sg.org,
	kyungmin.park@...sung.com, cw00.choi@...sung.com,
	akpm@...ux-foundation.org,
	Anton Vorontsov <anton.vorontsov@...aro.org>
Subject: Re: [PATCH v3 5/6] timerfd: Add support for deferrable timers

On Thu, 20 Feb 2014, Alexey Perevalov wrote:

> From: Anton Vorontsov <anton@...msg.org>
> 
> This patch implements a userland-side API for generic deferrable timers,
> per linux/timer.h:
> 
>  * A deferrable timer will work normally when the system is busy, but
>  * will not cause a CPU to come out of idle just to service it; instead,
>  * the timer will be serviced when the CPU eventually wakes up with a
>  * subsequent non-deferrable timer.
> 
> These timers are crucial for power saving, i.e. periodic tasks that want
> to work in background when the system is under use, but don't want to
> cause wakeups themselves.
> 
> The deferred timers are somewhat orthogonal to high-res external timers,
> since the deferred timer is tied to the system load, not just to some
> external decrementer source.

Again this changelog makes no sense. What's orthogonal to high-res
timers and why are they external?

So 5 out of 6 patches are a trainwreck in various degrees of
wreckage. A pretty impressive achievement.

Thanks,

	tglx
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