[T-Mobile Galaxy Note 4 General] AlkaliV2:
These tips are based in my study and experience of using different programs and techniques to get solid and stable performance from custom kernels. It's a long read, but a good read if you really want to minimize heat and maximize performance. This information works on any custom kernel that can be used with Synapse. This guide is aimed at beginner and intermediate users who are interested in custom kernel settings but don't know where to start. These are the most commonly optimized settings on Android.

***DVFS Rule #2 is exclusive to Samsung devices (so if you don't have a Samsung device don't use it!)***

Rule 1: What works for some won't work for others

- This has always been the most important rule of custom kernels. One person using Barry Allen governor, overclocked to 3.07 GHz, and not using intelliplug will never hit 70C while your phone using those same settings might immediately cause the phone to reboot. All synapse changes made to a device must be tested by you to ensure compatibility for your hardware. Some of you may be curious, if this is the case, why Google would have everyone use the interactive governor by default? I would respond to you that they originally assigned everyone to OnDemand while they worked to make a better and more compatible Interactive governor. But as you know there are a LOT of governors out there and knowing what is best for your device is to read and to test it. The good news is that once you find something that works well you can stick with it as long as you own the device.

Rule 2: DVFS (Dynamic Voltage and Frequency Scaling) Disabler

- This is mentioned in a few threads, but requires a repeat. Samsung uses DVFS to contol your CPU frequencies and voltage levels. This isn't an issue when you're running a stock kernel because it works in conjunction with MP-Decision to decide on the proper frequency level. When you're running emotion kernel you don't want DVFS to control anything. You want it to let Faux's Intellithermal work together with the kernel routines to shut down cores it doesn't need.

R2 Part 1: If your phone is running hot: Install Xposed, download Wanam Xposed (enable the module), Open Wanam, click "Advanced" menu, Uncheck "Enable TouchWiz DVFS" and reboot.

R2 Part 2: Following the reboot open Synapse, scroll over to CPU Drivers scroll down and put a checkbox in "Enable Intelli-hotplug", leave the rest alone, and click the check mark at the top of the screen to save changes. Scroll over one more screen to "Thermal" and put a check in the box, "Enable or Disable Intelli Thermal Control" and leave the settings below as they are unless you know what you are doing.

Note

: The phone will be still be warm for awhile, but if you give the phone a break and allow the heat to dissipate it should run cooler and more consistently with the added bonus of shutting down 3 out of the 4 cores unlike MP-Decision which always leaves 2 cores live. After doing this if you are noticing performance loss or stuttering it's time to find a new governor that makes the most of these settings. Which leads me to Rule 3....

Rule 3: Choosing a new governor

- This part is going to require some reading on your part, but I can assure you that it is worth your time. This guide http://xdaforums.com/general/general/ref-to-date-guide-cpu-governors-o-t3048957 by [MENTION=5811506]gsstudios[/MENTION] is OUTSTANDING (

please thank him while you are there

) and carries a LOT of information about the governors and other performance informations. So find something you like from the guide descriptions to try out and leave it in place for 24 hours or more as long as you aren't experiencing excessive lag or reboots. If it performs well under normal usage the next step is to watch battery life. There won't be a single governor that does everything perfectly, but finding something that fits your needs is key. And it's OKAY if you decide to stick with Interactive, it is a very well made governor and many are based off of that design, but I equate it to finding a good pair of shoes. Lots of things will protect your feet from the ground, but shoes that you enjoy and work well make all the difference in the world.

NOTE:

You can use Antutu for stability testing but do not pick a new governor and then run benchmarks and expect top score unless you chose the performance governor. Antutu specifically maxes out your device voltage and frequency to see what the device can handle which is not what intelliplug is for. If you are following this guide benchmarks are the least of your concerns.

Rule 4: Don't forget your Scheduler

- Believe it or not, everything runs off of your phone storage. So using an optimized scheduler for you device could make great strides in battery and performance improvements. Unlike choosing a governor, you can absolutely benchmark your flash memory to find out which scheduler works best for you. I only use one and I am going to shamelessly plug it here: I use Android Tuner to benchmark my flash speed with different schedulers and it works great for me. How it works:

Note

:To help with choosing where to start with schedulers you can use the guide I linked to above which will give you an idea of what to use. That guide has an exceptional amount of information about how these types of schedulers work and what you should use for getting what you want from your phone. What follows is my advice for testing benchmark write performance and those steps are completely optional, but it never hurts to see how your device does with your chosen scheduler.

R4 Part 1: Launch Android Tuner, from the main menu accept root, acknowledge that root is powerful, scroll all the way to the far left screen, choose "SD Card Read Speed", click "Benchmark in the center, and then notice at the top you have /storage/emulated/0 which is your faster internal memory (which you should optimize first) and then /storage/ExtSdCard which you can benchmark second.

R4 Part 2: When you are ready to benchmark choose your "I/O Scheduler" from the drop down menu and click "Run". Your results will be listed with the fastest read-ahead size on the left and the speed at which it read on the right. Higher = Better -- Then you would choose the other test size (10MB in my case) and you see which readahead value is the fastest for those files. If you manage to get a readahead that the 100MB and 10MB test highest values are the same, then you've won the lottery. Since that is almost impossible try to remember what your top 5 fastest are and choose the one that performs well in both tests. If you want to keep testing and check other schedulers for raw read speed just switch them at the top and re-run both tests.

After you've found which scheduler gives you the performance you want, go back to Synapse, scroll to "I/O" tab, and adjust pick your scheduler and readahead value, and finally click the check mark to apply it.

Rule 5: Undervolting (IMO) does more harm than good

- I'll let you Google it but it follows the rule of diminishing returns. You might be running Synapse and are able to undervolt 75mV and still cruise through menus and apps like it's no problem. But I promise you at some point the CPU is going to call for that voltage you starved it of and it will reboot. It's not a matter of if it will happen, but when it will happen. This comes down to your personal silicon and I do not recommend undervolting at all. Other more advanced users may disagree with me, but for the average user there are better ways to save battery and negate heat than starving your CPU and GPU at a kernel level. Especially with DVFS disabled.

And that's all I have for you. These tips work for any custom kernel that uses Synapse to manage their settings. I've personally test my setup with Emotion and the kernel we are not to speak of on XDA. If you like the idea of getting the most out of your device then a custom kernel might be for you, but it requires a lot of patience. If you just need something that works I definitely recommend the stock kernel because they really did a good job with the Lollipop release of our kernel.

I hope this helps some of you and I hope that everyone can take something away from this guide. Feel free to let me know if this helped you in some way or if you need some guidance on the topic. I'll do my best to backup my claims with proper research and documentation.

Thanks

Google - For research help and a great phone OS

Linux - The foundation of this OS

gsstudios - For his outstanding guide and work on researching this information (Definitely hit 'Thanks' on his post)

Note 4 ROM and Kernel Devs - we are very lucky to have a lot of great devs for our device; their work is appreciated and gives me something to write about

XDA and their members - where I've learned most everything about one of my favorite operating systems