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:


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+

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44 Comments

1. frustyak

Posts: 248; Member since: Mar 08, 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.

2. PapaSmurf

Posts: 10457; Member since: May 14, 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."

5. walkman800

Posts: 113; Member since: Aug 26, 2014

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

22. ThePython

Posts: 902; Member since: May 08, 2013

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

31. PapaSmurf

Posts: 10457; Member since: May 14, 2012

And this is how you look stupid. Optimizations = better battery life. Please log off and educate yourself.

32. ThePython

Posts: 902; Member since: May 08, 2013

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

21. SuperAndroidEvo

Posts: 4888; Member since: Apr 15, 2011

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

25. vincelongman

Posts: 5677; Member since: Feb 10, 2013

Google has finally add Qualcomm's NEON drivers in 5.1https://android.googlesource.com/device/lge/hammerhead-kernel/+/824f1e6 5.1 with encryptionhttps://i.imgur.com/1lcS0Oi.jpg 5.1 without encryptionhttps://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

27. hung2900

Posts: 966; Member since: Mar 02, 2012

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

29. vincelongman

Posts: 5677; Member since: Feb 10, 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

35. alvinl

Posts: 6; Member since: Dec 28, 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.

3. jpkelly05

Posts: 110; Member since: Nov 13, 2012

Nice article!

4. Mxyzptlk unregistered

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

6. DefinitiveKid

Posts: 261; Member since: May 15, 2013

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

7. TyrionLannister unregistered

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

8. DefinitiveKid

Posts: 261; Member since: May 15, 2013

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

9. Rorschach

Posts: 83; Member since: Apr 26, 2013

TW > stock Android

12. Andrew5190

Posts: 55; Member since: Oct 23, 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 :)

15. Awalker

Posts: 1973; Member since: Aug 15, 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.

37. DroidMystic

Posts: 91; Member since: Oct 31, 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.

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 ?

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.

13. RebelwithoutaClue unregistered

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

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.

24. vincelongman

Posts: 5677; Member since: Feb 10, 2013

Actually Google has finally add Qualcomm's NEON drivers in 5.1https://android.googlesource.com/device/lge/hammerhead-kernel/+/824f1e6 5.1 with encryptionhttps://i.imgur.com/1lcS0Oi.jpg 5.1 without encryptionhttps://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/nexus6https://www.reddit.com/r/nexus6/comments/2ytny6/nexus_6_51_improved_read_and_write_speeds_with/ And post about it from the Franco kernel devhttps://plus.google.com/+FranciscoFranco1990/posts/3RKjDGjjPQ7

33. TyrionLannister unregistered

Thanks for the information.

14. nodes

Posts: 1158; Member since: Mar 06, 2014

Android is still catching up.

20. IT-Engineer

Posts: 533; Member since: Feb 26, 2015

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

17. yowanvista

Posts: 341; Member since: Sep 20, 2011

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

18. TheGunnyPT

Posts: 252; Member since: Feb 12, 2015

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

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