linux-kernel - Re: suspend blockers & Android integration

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Date:	Sun, 6 Jun 2010 14:18:36 +0300
From:	Felipe Contreras <felipe.contreras@...il.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Arve Hjønnevåg <arve@...roid.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>, tytso@....edu,
	Brian Swetland <swetland@...gle.com>,
	Neil Brown <neilb@...e.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Alan Stern <stern@...land.harvard.edu>,
	Felipe Balbi <felipe.balbi@...ia.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Florian Mickler <florian@...kler.org>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	Linux PM <linux-pm@...ts.linux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	James Bottomley <James.Bottomley@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Kevin Hilman <khilman@...prootsystems.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: suspend blockers & Android integration

2010/6/6 Arjan van de Ven <arjan@...radead.org>:
> On Sat, 5 Jun 2010 14:26:14 -0700
> Arve Hjønnevåg <arve@...roid.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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