Re: [PATCH v3 5/6] timerfd: Add support for deferrable timers
From: Thomas Gleixner
Date: Thu Feb 20 2014 - 06:09:45 EST
On Thu, 20 Feb 2014, Alexey Perevalov wrote:
> From: Anton Vorontsov <anton@xxxxxxxxxx>
>
> 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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