[Q] More info on the Android OS bug. Suspend process , wakelocks and battery life.

Hello all,

I first posted this in Q&A on the home forum. There doesn't seem to be any interest so I thought I'd post it here again. Below is what I wrote on the original post.

"If you’ve been supremely annoyed with the AOS bug like I have , here’s some interesting information I’ve found (Did a search and it appears no one else has found this yet). It’s a paper written (in 2010)by Rafael J. Wysocki which touches deep into the subject. What I hope is that it will help some developers understand this bug and ultimately integrate a work around / fix as soon as possible. Hopefully this will help some users understand what is going on with their phones as well.

I have and Epic 4g Touch and all the ROMS I’ve tried have this bug but according to the article, looks like a kernel problem. My suspend / events/0 processes runs for a long time, eating up cpu and I don’t have it as bad as some people but thought it's worth mentioning.

Basically what I get from the paper is that…
1. The suspend (and by association the events/0 process) process is Google’s implementation of a power management system, an add on to the Linux Kernel
2. That the wakelock / suspend feature is , to make a long story short , not working the way it’s supposed to.
3. “Poorly” written apps, or apps that are written without the inner workings of how suspend /wakelocks work, will trigger this bug. This can be ANYTHING.
4. Supposedly, kernel version 2.6.37 will fix this. The Epic 4g Touch kernels are all .35 as far as I know which explains the fact that so many Epic 4g Touch owners complain about this.

Would love for the smarter than me people to give their take on this?

Since this is my first post, it won't let me post a link. Do a google search for Rafael Wysocki suspend_blockers.pdf and it should be the first link that shows up."

Hopefully there's more interest here!

Danial, thanks for the reply. Not sure if it was intentional but that's not the document I was referring to. However it looks like useful info and simplifies some of the explanations and even uses the the document written by Wysocki as a reference so thanks for that.

Bump! for battery life lovers!!!

pcmanager said:

how do I check to see if this bug is causing battery drain on my phone. thanks!

Sent from my SPH-D710 using Tapatalk

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If you go to Settings, About Phone, Battery usage, you'll see "Android OS" take an unusal amount of battery time. Mine varies from 25-80%, some others I've read, consistently get 80%. You should be running on battery for a while before you check this since if you've only been on battery for a few hours, that stats may be misleading.

A more precise way is also to download the free Battery monitor Widget, and in the statistics section, you'll see the processes "suspend" and "events/0" take hours of usage when it shouldn't. You also may see *wakelock* take up hours of time.

Some dwho have it bad, download watchdog, and monitor on the fly, which processes go over a certain amount of % usage. If your batter drains quickly, suggest this route to confirm its suspend and events/0.

faceyourfaces said:

I'm assuming you were talking about this site, which was the second search result:
http://lwn.net/images/pdf/suspend_blockers.pdf

As a side note, my Android OS is at 7% of my battery usage right now.

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May I ask,

1. How long your phone is on battery for?
2. Kernel Version?
3. ROM?

Would love to be @ 7% for Android OS!

pcmanager said:

thanks for all those great infos. my android os is usually under 10 percent after several hours of use so I don't think that is buggin me. Could you explain exactly what a wakelock is? I know I could use the search button but the info you provide here in this thread might help a lot of other people trying to resolve battery drainage issues. Thanks!

Sent from my SPH-D710 using Tapatalk

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A wakelock is, as I understand it, a process in the Android kernel that temporarily tells the Android device to hold off sleeping (stop the suspend process).

This allows for a process , application or device (such as your wi fi antenna) to turn back on and do what it needs to do. The suspend process is suppose to tell the phone to go back to sleep but with this bug, either or can get stuck and therefore use up more cpu that it's supposed to.

pcmanager said:

1. How long on battery 1:15
2. Kernel Version EL29
3. ROM StrongSteve blue, Odex
4. Android OS 3%


I will let you know what the OS % is at the end of the day before the battery dies ......

Would love to be @ 7% for Android OS!

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Sent from my SPH-D710 using Tapatalk[/QUOTE]

Interesting, I'm on EL29, have used Strong Steve's ROM but it still persists for me. Next thing I will try is to install Steve's ROM only, no additional apps.

I've gotten 2 days , 9 hours battery life (on light use, about 3 hours screen time, lowest setting) my last round but I've Juice Defender configured it to heck and undervolted as well. I think if I figure out what app may be contributing to this I just may get 3 days, may be 4 days battery life.

thanks for the info!

gk325 said:

So i have system updates always running. When I go to try and update PRL and firmware etc, it gives me an error. I assume I need to re-flash a stock ROM, then update? I wonder if my problem is this: My used my phone for a few weeks, then ported over a new number. Under phone info, it still shows the original number. It uses the original number for a hotspot confirmation. But my phone clearly has a new number. Is this need for the phone to update causing the battery drain?

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PRL's (and profiles) should update despite having a custom ROM. Firmware won't however.

I think it's unlikely that the fact you can't update is causing a battery drain. To be sure, you need to find out which process the phone uses to do updates and see if they are taking up alot of CPU (OS monitor or battery monitor widget will help you with CPU usage.)

I think you simply have the OS bug like the rest of us.

pcmanager said:

EOD report...

1. How long on battery 1:15
2. Kernel Version EL29
3. ROM StrongSteve blue, Odex
4. Android OS 3%

1. How long on battery 9:24
2. Kernel Version EL29
3. ROM StrongSteve blue, Odex
4. Android OS 21%
5. Display on 2:09
6. Percent battery left 29%


Not a great day for battery stats but i did change my modem from ek02 to el29 last night trying to solve a gmail keeps sending issue i am having. Last time i was on el29 it seemed to consume more juice so i switched back to eko2.

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Yeah your battery life is dismal but the Android OS percentage is not nearly what I would expect it to be if the bug was causing this.

I would at least try a free battery saving app if you haven't already. You could probably get a few extra hours out of it.

Might want to turn 4g off also and see how much more mattery life you get.