Re: suspend blockers & Android integration

[Arve Hjønnevåg]

2010/6/5 Arjan van de Ven <arjan@xxxxxxxxxxxxx>:
> On Sat, 5 Jun 2010 14:26:14 -0700
> Arve Hjønnevåg <arve@xxxxxxxxxxx> wrote:
>
>> On Sat, Jun 5, 2010 at 9:28 AM, Arjan van de Ven
>> <arjan@xxxxxxxxxxxxx> wrote:
>> > On Sat, 05 Jun 2010 11:54:13 +0200
>> > Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>> >
>> >> On Fri, 2010-06-04 at 17:10 -0700, Arve Hjønnevåg wrote:
>> >> > > Trusted processes are assumed to be sane and idle when there is
>> >> > > nothing for them to do, allowing the machine to go into deep
>> >> > > idle states.
>> >> > >
>> >> >
>> >> > Neither the kernel nor our trusted user-space code currently
>> >> > meets this criteria.
>> >>
>> >> Then both need fixing. Really, that's the only sane approach.
>> >
>> > fwiw... in MeeGo we're seeing quite good idle times (> 1 seconds)
>> > without really bad hacks.
>> >
>>
>> We clearly have different standards for what we consider good. We
>> measure time suspended in minutes or hours, not seconds, and waking up
>> every second or two causes a noticeable decrease in battery life on
>> the hardware we have today.
>
> I guess I'm spoiled working with (unreleased) hardware that knows how
> to power gate ;-)
>
>
>>
>> > the kernel has a set of infrastructure already to help here (range
>> > timers, with which you can wakeup-limit untrusted userspace crap),
>> > timer slack for legacy background timers, etc etc.
>>
>> Range timers allows the kernel to align different timers so they don't
>> each bring the cpu out of idle individually. They do not eliminate
>> timers or make individual timers fire less often.
>
> you're incorrect.
> With range timers you can control the rate at which timers fire just
> fine.
>
> For example if the Adobe Flash player puts a timer every 10
> milliseconds (yes it does that), and you give it a 3.99 seconds range,
> it will fire its timers every 4 seconds.... unless other activity
> happens independently, at which point it'll align with that instead.
>

If you do that what you are delivering is nowhere close to what the
app asked for. You don't need range timers for this, you could just as
well add 4 seconds to all normal timers.

-- 
Arve Hjønnevåg
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/