Re: [linux-pm] [PATCH 0/8] Suspend block api (version 6)

[Daniel Walker]

On Thu, 2010-05-13 at 13:23 -0700, Tony Lindgren wrote:
> * Matthew Garrett <mjg@xxxxxxxxxx> [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.

Couldn't you just use priorities (nice), or cgroups to deal with that?
I'm sure there is a way to limit an apps runtime, so the system does go
idle sometimes.

> > 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.

There are deferrable timers already in Linux.. It seems like it would
just be an extension of that.

Daniel

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