Re: Attempted summary of suspend-blockers LKML thread

Raj Kumar
2010-08-03T12:26:51Z

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Hi Arve and Alan,

I have some questions regarding the Android early suspend and ACPI that are as follows:

1) If i see the early suspend features which is for android, it is if the user presses power off

the button and on button for late resumes. The question is if there is mobile platform,

then when user presses power off button, will the early suspend handlers will be called

at that time?

what usecase android early suspend handles?

2) Regarding ACPI which is more bios centric, will the drivers need to implement suspend/resume

as for normal OS use case scenarios?

Regards

Raj

> Date: Mon, 2 Aug 2010 21:56:10 -0700
> Subject: Re: Attempted summary of suspend-blockers LKML thread
> From: arve@android.com
> To: paulmck@linux.vnet.ibm.com
> CC: arjan@infradead.org; linux-pm@lists.linux-foundation.org; linux-kernel@vger.kernel.org; mjg59@srcf.ucam.org; pavel@ucw.cz; florian@mickler.org; rjw@sisk.pl; stern@rowland.harvard.edu; swetland@google.com; peterz@infradead.org; tglx@linutronix.de; alan@lxorguk.ukuu.org.uk
>
> On Sun, Aug 1, 2010 at 6:10 PM, Paul E. McKenney
> <paulmck@linux.vnet.ibm.com> wrote:
> > On Sun, Aug 01, 2010 at 03:47:08PM -0700, Arjan van de Ven wrote:
> ...
> >> Another one: freezing whole cgroups..... we have that today. it
> >> actually works quite well.... of course the hard part is the decision
> >> what to put in which cgroup, and at what frequency and duration you let
> >> cgroups run.
> >
> > Indeed, the Android guys seemed to be quite excited by cgroup freezing
> > until they thought about the application-classification problem.
> > Seems like it should be easy for some types of applications, but I do
> > admit that apps can have non-trivial and non-obvious dependencies.
> >
>
> The dependencies is what made this solution uninteresting to us. For
> instance, we currently use cgroup scheduling to reduce the impact of
> some background tasks, but we occasionally saw a watchdog restart of
> the system process were critical services were waiting on a kernel
> mutex owned by a background task for more than 20 seconds. If we froze
> a cgroup instead, we would not hit this particular problem since tasks
> cannot be frozen while executing kernel code the same way they can be
> preempted, but nothing prevents a task from being frozen while holding
> a user-space resource.
>
> --
> Arve Hjønnevåg
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