Re: Attempted summary of suspend-blockers LKML thread

david
2010-08-06T00:16:44Z

On Thu, 5 Aug 2010, Brian Swetland wrote:

> On Thu, Aug 5, 2010 at 4:03 PM, Paul E. McKenney
> <paulmck@linux.vnet.ibm.com> wrote:
>>>> so what would wake a phone up from suspend where the phone should go back to
>>>> sleep in under a second?
>>>
>>> Here are some real-world examples from shipped android devices:
>>> - battery gauging happens every 10 minutes, need to wake long enough
>>> to chatter with the 1w interface and make sure the battery is not
>>> exploding
>>> - always on mail/im/calendar/etc sync often has network events that
>>> happen every 5-10 minutes which cause devices to briefly wake up and
>>> return to sleep
>>> - gps tracker app might wake every couple minutes or every n gps
>>> events to log location
>>> - low power audio subsystems can wake you up every 1-4 seconds (pcm)
>>> or 1-4 minutes (mp3) to fetch more data
>>
>> Interesting!
>>
>> So for an mp3 playback, does an Android suspend between data fetches?
>
> It can if the latency is long enough (which is why I point out low
> power audio which is usually high latency). For low latency (system
> sounds, etc) 10-25ms between buffers it's not practical to fully
> suspend but we will go to the lowest power state in idle if possible.

the playback is able to continue even with all the clocks stopped? that
surprises me. I would hav expected it to be able to sleep while playing
audio, but not do a full suspend.

David Lang