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Date: Thu, 13 May 2010 13:23:20 -0700
From: Tony Lindgren <tony@atomide.com>
To: Matthew Garrett <mjg@redhat.com>
Cc: Alan Stern <stern@rowland.harvard.edu>, Paul Walmsley <paul@pwsan.com>,
       Arve =?utf-8?B?SGrDuG5uZXbDpWc=?= <arve@android.com>,
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       Liam Girdwood <lrg@slimlogic.co.uk>
Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 6)
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* Matthew Garrett <mjg@redhat.com> [100513 13:03]:
> On Thu, May 13, 2010 at 01:00:04PM -0700, Tony Lindgren wrote:
> 
> > The system stays running because there's something to do. The system
> > won't suspend until all the processors hit the kernel idle loop and
> > the next_timer_interrupt_critical() returns nothing.
> 
> At which point an application in a busy loop cripples you.

Maybe you could deal with the misbehaving untrusted apps in the userspace
by sending kill -STOP to them when the screen blanks? Then continue
when some event wakes up the system again.

> I think we could implement your suggestion more easily by just giving
> untrusted applications an effectively infinite amount of timer slack,
> but it still doesn't handle the case where an app behaves excrutiatingly
> badly.

Hmm, if you use timer slack then you still need to search through
the whole timer list instead of a smaller critical timer list.
Both ways sound doable though.

Regards,

Tony