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Posted May 6, 2017 15:01 UTC (Sat) by fratti (guest, #105722)
In reply to: Suspend/Resume by flussence
Parent article: 4.12 Merge window part 1

Ah, I did not realise phones entered such a deep sleep when the screen was locked. I always figured if that was the case, the wireless connections and such would drop, but I guess these are handled by external chips and they can wake up the main processor when something interesting is happening.

Thanks for the insight on this!

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Posted May 12, 2017 9:55 UTC (Fri) by oldtomas (guest, #72579) [Link]

> but I guess these are handled by external chips

Well, kind of, only that they are subsystems (with CPU, RAM, ROM)... on the same chip. Cost pressure has forced maufacturers to move next to everything into That One Big Chip.

Although unrelated, those two articles have the nice collateral effect to update one's idea of the current State of the Phone:

https://googleprojectzero.blogspot.de/2017/04/over-air-ex...
https://googleprojectzero.blogspot.de/2017/04/over-air-ex...

(and, btw, it's through LWN that I was made aware of them).

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Posted May 16, 2017 15:42 UTC (Tue) by flussence (guest, #85566) [Link]

Wi-Fi standards are a twisty maze of layered hacks to facilitate power saving. Chances are your phone is mostly disconnected when it's switched off, but reconnects fast enough when it wakes up to put on a convincing illusion that it's always-on.

Most Android phones also have Play Services and its server-push API, so instead of O(n) apps polling for new messages separately it's a single connection to Google's servers. (Anecdotally, I found my phone's battery life tripled after removing the Google-ware, but that's probably more to do with it triggering the OOM killer constantly...)