Re: Attempted summary of suspend-blockers LKML thread

From: Brian Swetland
Date: Thu Aug 05 2010 - 20:13:44 EST

On Thu, Aug 5, 2010 at 4:03 PM, Paul E. McKenney
<paulmck@xxxxxxxxxxxxxxxxxx> 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.

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