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Message-Id: <201006052025.11526.rjw@sisk.pl>
Date: Sat, 5 Jun 2010 20:25:11 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Arve Hjønnevåg <arve@...roid.com>
Cc: Matt Helsley <matthltc@...ibm.com>,
Thomas Gleixner <tglx@...utronix.de>,
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
On Saturday 05 June 2010, Arve Hjønnevåg wrote:
> 2010/6/4 Matt Helsley <matthltc@...ibm.com>:
> > On Fri, Jun 04, 2010 at 05:39:17PM -0700, Arve Hjønnevåg wrote:
> >> On Fri, Jun 4, 2010 at 5:05 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> >> > On Sat, 5 Jun 2010, Rafael J. Wysocki wrote:
> >
> > <snip>
> >
> >>
> >> > With the cgroup freezer you can "suspend" them right away and
> >> > just keep the trusted background task(s) alive which allows us to
> >> > go into deeper idle states instead of letting the crapplications
> >> > run unconfined until the download finished and the suspend
> >> > blocker goes away.
> >> >
> >>
> >> Yes this would be better, but I want it in addition to suspend, not
> >> instead of it. It is also unclear if our user-space code could easily
> >> make use of it since our trusted code calls into untrusted code.
> >>
> >
> > Perhaps I'm misunderstanding, but suspend and the cgroup freezer
> > interoperate well today -- you don't have to choose one or the other.
> > If you've discovered otherwise I'd consider it a bug and would like to
> > hear more about it.
> >
>
> I'm not aware of any bug with combining both, but we cannot use
> suspend at all without suspend blockers in the kernel (since wakeup
> events may be ignored)
The more I think of it, the more it appears to me that the problem of
lost wakeup events can actually be solved without suspend blockers.
I'll send a bunch of patches to address this issue, probably tomorrow.
> and I don't know how we can safely freeze
> cgroups without funneling all potential wakeup events through a
> process that never gets frozen.
If your untrusted apps get called by the trusted ones, they aren't really
untrusted in the first place.
>From what you're saying it follows that you're not really willing to accept
any solution different to your suspend blockers. Is that really the case?
Rafael
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