linux-kernel - Re: suspend blockers & Android integration

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Date:	Mon, 7 Jun 2010 16:34:29 -0700
From:	Arve Hjønnevåg <arve@...roid.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>, tytso@....edu,
	Brian Swetland <swetland@...gle.com>,
	Neil Brown <neilb@...e.de>,
	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>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: suspend blockers & Android integration

2010/6/6 Thomas Gleixner <tglx@...utronix.de>:
> On Sat, 5 Jun 2010, Arve Hjønnevåg wrote:
>> 2010/6/5 Thomas Gleixner <tglx@...utronix.de>:
>> > On Sat, 5 Jun 2010, Arve Hjønnevåg wrote:
>> >> 2010/6/5 Thomas Gleixner <tglx@...utronix.de>:
>> >> > On Sat, 5 Jun 2010, Arve Hjønnevåg wrote:
>> >> >> >> > That download might take a minute or two, but that's not an
>> >> >> >> > justification for the crapplication to run unconfined and prevent
>> >> >> >> > lower power states.
>> >> >> >> >
>> >> >> >>
>> >> >> >> I agree, but this is not a simple problem to solve.
>> >> >> >
>> >> >> > Not with suspend blockers, but with cgroup confinement of crap, it's
>> >> >> > straight forward.
>> >> >> >
>> >> >>
>> >> >> I don't think is is straight forward. If the a process in the frozen
>> >> >> group holds a resource that a process in the unfrozen group needs, how
>> >> >> do deal with that?
>> >> >
>> >> > I'm going to fix the framework which puts the group into freeze state
>> >> > w/o making sure that there is no held shared resource. Come on it's
>> >> > not rocket science.
>> >> >
>> >>
>> >> I'm not sure which framework you are talking about here, but I don't
>> >> think there is a single framework that knows about all shared
>> >> resources.
>> >
>> > Damn, it's not me talking about "our framework", you are mentioning
>> > when it fits your needs.
>>
>> You said you were going to fix the framework. I did know if you were
>> talking about the cgroup framework, or the android user-space
>> frameworks. I don't think either has knowledge about all shared
>> resources.
>
> The cgroup freezer makes sure that there are no in kernel resources
> blocked. Of course the user space side has to do the same and it's not
> rocket science.
>

It is much easier to make sure there are no kernel resources held than
that there are no resources held in user-space. The kernel threads
have to return to a safe location before they get frozen, where user
threads are just frozen wherever they are.

-- 
Arve Hjønnevåg
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