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Android 5.1 Lollipop brings non-trivial performance and efficiency improvements to the Nexus 6

Posted: , by Chris P.

Android 5.1 Lollipop brings non-trivial performance and efficiency improvements to the Nexus 6

While the majority of Nexus 6 owners are still waiting for the now official Android 5.1 Lollipop to start seeding, power users and developers have already had the chance to not just load the new firmware image on their own units manually, but to even dig a little deeper in order to make sense of the changes Google included.

According to Francisco Franco, the developer behind the extremely popular custom Android franco.kernel, the changes are not at all trivial. Writing on his Google+ page, Francisco addresses speculation that has the Nexus 6 feeling even smoother under Lollipop 5.1. According to the dev, this is no placebo, and people are right.

Apparently, apart from improvements made to the ART runtime and any other possible optimizations of code, the new firmware also forces the Nexus 6's quad-core Qualcomm Snapdragon 805 processor to run all four cores at all times:

"... the device is now running full quad-core mode all the time which helps tremendously because the Kernel task scheduler can distribute the workload through all these cores so you'll get the perception that the device is not hanging anymore."

This is where your performance gain comes from. As for the part about better efficiency, we're told that Google has disabled something called 'built-in thread migration routines' that helps your battery survive for longer. Put simply, the feature basically kicks in whenever one task has to be migrated to a different from its current CPU core. In those instances, the task scheduler would before tell the destination core to match or exceed the current frequency of the origin core, lowering perceived lag. Since these migrations can apparently occur as often as every 20 ms, disabling them equals savings.

A good time to be a Nexus 6 user, no?

source: Google+

45 Comments
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posted on 12 Mar 2015, 11:03 7

1. frustyak (Posts: 210; Member since: 08 Mar 2010)


I hope the improvement in efficiency is real, because when I see "the device is now running full quad-core mode all the time" I think "battery drain". We'll see.

posted on 12 Mar 2015, 11:20 3

2. PapaSmurf (Posts: 10457; Member since: 14 May 2012)


You forgot to continue reading before posting a comment:

"This is where your performance gain comes from. As for the part about better efficiency, we're told that Google has disabled something called 'built-in thread migration routines' that helps your battery survive for longer."

posted on 12 Mar 2015, 11:25 6

5. walkman800 (Posts: 113; Member since: 26 Aug 2014)


I think he read it, he's just doubting whether improved performance will outweigh every effort taken in improving battery efficiency.

posted on 12 Mar 2015, 14:55

22. ThePython (Posts: 897; Member since: 08 May 2013)


...and this is how you burn an internet smartass.

posted on 12 Mar 2015, 19:35 2

31. PapaSmurf (Posts: 10457; Member since: 14 May 2012)


And this is how you look stupid. Optimizations = better battery life.

Please log off and educate yourself.

posted on 12 Mar 2015, 21:27

32. ThePython (Posts: 897; Member since: 08 May 2013)


Aw, how adorable. I'm well educated, thank you.

posted on 12 Mar 2015, 13:42

21. SuperAndroidEvo (Posts: 4857; Member since: 15 Apr 2011)


Waiting for Chroma to update to Android 5.1. The developer said maybe this weekend! YES!!!!!

posted on 12 Mar 2015, 15:50

25. vincelongman (Posts: 4576; Member since: 10 Feb 2013)


Google has finally add Qualcomm's NEON drivers in 5.1
https://android.googlesource.com/device/lge/hammerhead-kernel/+/824f1e6

5.1 with encryption
https://i.imgur.com/1lcS0Oi.jpg
5.1 without encryption
https://i.imgur.com/oeFolJc.png

Before the CPU had to do the encryption/decryption, causing a big performance hit and battery drain
So it will probably have better battery life than before, even with it being quad-core all the time now

posted on 12 Mar 2015, 18:55

27. hung2900 (Posts: 956; Member since: 02 Mar 2012)


Not only that. By this way, Google bypasses the s**tty CPU hotplugging, which causes lags.

posted on 12 Mar 2015, 19:27

29. vincelongman (Posts: 4576; Member since: 10 Feb 2013)


Yea, most custom kernels have their own CPU hotplugs

Also there's one called Trinity kernel which also has all 4 cores enabled at once

But in my experience Franco's has the best battery life, it has 2 cores always enabled, with Franco's own hotplug

posted on 13 Mar 2015, 02:56

35. alvinl (Posts: 6; Member since: 28 Dec 2013)


i actually had my phone off the plug at 10:12am and got home at 12:56am not pm with 65% left. I have the nexus 5.

posted on 12 Mar 2015, 11:20

3. jpkelly05 (Posts: 100; Member since: 13 Nov 2012)


Nice article!

posted on 12 Mar 2015, 11:25

4. Mxyzptlk (Posts: 14191; Member since: 21 Apr 2012)


Well let's hope Google ironed all of the nasty bugs out.

posted on 12 Mar 2015, 11:26 1

6. DefinitiveKid (Posts: 219; Member since: 15 May 2013)


Damn, just when I had made up my mind about not buying the N6 and waiting for the Galaxy S6...

posted on 12 Mar 2015, 11:28 5

7. TyrionLannister (unregistered)


The S6 will get the android 5.1 too, so your reason is useless.

posted on 12 Mar 2015, 11:31 4

8. DefinitiveKid (Posts: 219; Member since: 15 May 2013)


I know I know but still TW on top, which is the reason why I'm hesitating in the first place.

posted on 12 Mar 2015, 11:51 9

9. Rorschach (Posts: 83; Member since: 26 Apr 2013)


TW > stock Android

posted on 12 Mar 2015, 12:07 4

12. Andrew5190 (Posts: 55; Member since: 23 Oct 2014)


I'll admit I miss features of TW sometimes, but usually I remember how often I used them when I had them at my disposal, then I forget it.

But if you like Touchwiz, more power to ya! Choice is the best thing :)

posted on 12 Mar 2015, 12:17

15. Awalker (Posts: 1577; Member since: 15 Aug 2013)


...in your opinion. A clean slate that I can add to is better than having a bloated slate in my opinion. It's the reason why I stop buying Samsung devices although I may get the S6 Edge only because I like the look of it.

posted on 13 Mar 2015, 04:40

37. DroidMystic (Posts: 83; Member since: 31 Oct 2014)


It's not useless be cause the Nexus 6 does have it now and I still be in advance on update. All depends on what he really want.

posted on 12 Mar 2015, 11:55

10. seven7dust (unregistered)


So is encryption still on and is it improved ! why can iPhones from 2011 and even Windows work with encryption but it slows down a Nexus ,I still don't get it ?

posted on 12 Mar 2015, 12:05 1

11. TyrionLannister (unregistered)


Apple used a separate chip for hardware based encryption since the 3Gs. So, the CPU doesn't have to do it.

For Nexus 6, it doesn't have a dedicated hardware to do it. Hence the CPU has to do it making it inefficient. In contrast, Nexus 9 is ARMv8 based and hence has hardware based encryption too.

Nexus 6 is an unfortunate device that got slower due to this.

posted on 12 Mar 2015, 12:13 1

13. RebelwithoutaClue (Posts: 3029; Member since: 05 Apr 2013)


To my understanding, the 805 has a crypt module but Google doesnt use it. Don't know why though.https://www.qualcomm.com/news/snapdragon/2014/11/07/cryptographic-module-snapdragon-805-fips-140-2-certified

posted on 12 Mar 2015, 12:18

16. TyrionLannister (unregistered)


Yeah, I also heard somewhere about that. But I don't think it's as efficient as ARMv8 one which has it embedded in the architecture itself.

But yeah, shame on google for not implementing it.

posted on 12 Mar 2015, 15:43

24. vincelongman (Posts: 4576; Member since: 10 Feb 2013)


Actually Google has finally add Qualcomm's NEON drivers in 5.1
https://android.googlesource.com/device/lge/hammerhead-kernel/+/824f1e6

5.1 with encryption
https://i.imgur.com/1lcS0Oi.jpg
5.1 without encryption
https://i.imgur.com/oeFolJc.png

There's still a minor performance hit, like you said its not as good as ARMv8

Here's some dicussion from r/nexus6
https://www.reddit.com/r/nexus6/comments/2ytny6/nexus_6_51_improved_read_and_write_speeds_with/

And post about it from the Franco kernel dev
https://plus.google.com/+FranciscoFranco1990/posts/3RKjDGjjPQ7

posted on 12 Mar 2015, 22:02

33. TyrionLannister (unregistered)


Thanks for the information.

posted on 12 Mar 2015, 12:15

14. nodes (Posts: 747; Member since: 06 Mar 2014)


Android is still catching up.

posted on 12 Mar 2015, 13:29 3

20. IT-Engineer (Posts: 90; Member since: 26 Feb 2015)


Android is catching up to it's Legend, mean while apple is 3 years behind.

posted on 12 Mar 2015, 12:48 1

17. yowanvista (Posts: 340; Member since: 20 Sep 2011)


It also comes with the new v104 Adreno 420 drivers which bring full OpenGL ES3.1 support.

posted on 12 Mar 2015, 13:21 1

18. TheGunnyPT (Posts: 252; Member since: 12 Feb 2015)


Always nice to see any phone being boosted in performance, especially the Nexus 6 beast :D!

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