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Date: Sun, 6 Jun 2010 14:18:36 +0300
Message-ID: <AANLkTimjtNhtI0CuxYd0wdN_svthC-vl9_a5abDS2yyo@mail.gmail.com>
Subject: Re: suspend blockers & Android integration
From: Felipe Contreras <felipe.contreras@gmail.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>,
       Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>,
       tytso@mit.edu, Brian Swetland <swetland@google.com>,
       Neil Brown <neilb@suse.de>, Thomas Gleixner <tglx@linutronix.de>,
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       Florian Mickler <florian@mickler.org>,
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2010/6/6 Arjan van de Ven <arjan@infradead.org>:
> On Sat, 5 Jun 2010 14:26:14 -0700
> Arve Hjønnevåg <arve@android.com> wrote:
>> > the kernel has a set of infrastructure already to help here (range
>> > timers, with which you can wakeup-limit untrusted userspace crap),
>> > timer slack for legacy background timers, etc etc.
>>
>> Range timers allows the kernel to align different timers so they don't
>> each bring the cpu out of idle individually. They do not eliminate
>> timers or make individual timers fire less often.
>
> you're incorrect.
> With range timers you can control the rate at which timers fire just
> fine.

I was wondering... Currently GLib user-space aligns itself to fire
burst of work at second boundaries without the need for IPC. But if
you want to align beyond one second you need multi-process alignment.
Say, one application says: wake me up between 30s and 1m. And the
other one says: wake me up between 10m and 20m. They could very well
align at some point if there was a central process keeping track of
all the timers.

Does the kernel provide something to solve that problem already?

-- 
Felipe Contreras
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