[Xiaomi Mi 4i] haikalizz:
The Introduction

I'm about to tell you how to get buttery smooth, lag free performance with insanely good battery life, using an old school governor featured in practically every kernel... This tweak is applicable to every phone with any ROM or kernel--stock or custom--that provides the Interactive Governor.

Yeah, yeah... everyone promises good battery with great performance, but who actually delivers? Maybe it isn't as smooth as you want, or maybe it requires something your kernel or ROM don't support. Or maybe the battery life promises just aren't what you expected. There's always some awful compromise. Not here!

This isn't a guide to get 36 hour battery life... provided you never use your phone. That's deep sleep optimization, which is lovely and all, but what good is the phone if you can never use it?! And with the new Marshmallow Doze feature, this strategy is becoming a think of the past. What I'm talking about is 7-14 hour screen on, actual hands-on usage times! Without compromising anything, you can get 7-8 hour screen on usage with regular, no-compromise usage habits: daytime visible screen brightness, both radios on, sync on, network location on, all the regular usage features, the whole kit and kaboodle... all smooth as a baby's butt and snappy as a Slim Jim! (Up to 14+ hours if you can stand minimum brightness and WiFi-only with a custom ROM and other stuff turned off! And this is with stock voltages and full frequency range--you'll likely get even more if you choose to optimize those as well!)

However, it should be noted that this does not apply to gaming, heavy camera use, etc. Anything that is an automatic battery killer in and of itself. There's nothing that can be done about anything that forces the phone to utilize its maximum resources all the time. But you should know that by now. Further, this guide is about optimizing the CPU as much as possible. It does not cover things like eliminating wakelocks so your phone sleeps well, removing unnecessary and battery draining stock apps, keeping your screen brightness down*, and all that stuff that's been covered in other posts ad infinitum. Those optimizations are up to you.

*At least on the Mi4i, you shouldn't be turning your screen brightness above about 50%. It should be more than viewable in sunlight at that brightness, and keep in mind that the brightness power requirements increase exponentially, so a 100% bright LCD screen will use about 3.5-4.5x more power than a 60% bright screen. I don't see that fact brought up often, so I thought I'd mention it here.

After a bit of tweaking and experimenting, I developed some settings that provide absolutely incredible battery life, buttery smooth performance, and a lag free experience. And you don't need a fancy governor, or a custom kernel, custom clock rates, or even a Mi4i. This will work on any ROOTed phone with the Interactive governor!

The Nitty Gritty

Before I lay out all the settings so you can blindly enter them into your governor control, I should to explain some of the principals I employed to get the results I did. The primary thing to understand before I do is: little might you know, the settings in the Interactive governor can be tweaked on a clock range basis. That is to say, you can finely control how the governor responds at a variety of clock rates, thus better dictating how it should operate under various loads. This is integral to the configuration, because it means the difference between jumping from the slowest speed to the highest speed under load and sustaining lower clock speeds for tasks that don't really require higher clock speeds.

By default, the Interactive governor will jump from lowest speed to a "nominal" speed under load, and then scale up from that speed as load is sustained. That is lovely, but still too twitchy to provide serious efficiency and power savings. It spends most of its time at 2 or 3 clock speeds and barely hits other clock speeds that are ideal for other tasks or usage patterns.

Instead, what we want to do is configure it to handle different types of loads in different ways. A load suited for scrolling through a webpage is not the same as a load suited for downloading/processing streaming video is not the same as a load suited for snappy loading of an app is not the same as a load suited for high performance gaming. Every kind of load has different tolerances at which their minimal speed is indistinguishable from their maximal speed.

Nominal Clock Rates

Nominal clock rates are the minimum CPU clock rates that perform a given task smoothly and without stuttering or lag. To find the nominal clock rate for a given task, turn on only the first CPU using the Performance governor and turn them both down incrementally until you find the minimum clock rate that works best for what you're trying to do, without introducing hiccups. (If you have a CPU or kernel that hotplugs individual cores, multiply that clock speed by your number of cores.) Keep the 2nd CPU on the Powersave governor with the lowest frequency your kernel supports. (Or turn it off completely if hotplugging allows.)

(Note: If your device supports per-core hotplugging, you might be better off using the old guide to determine your nominal clock rates. The Mi4i and all current kernels only support hotplugging entire CPUs, so your results may vary if you use any other device.)

For example, on my Mi4i, scrolling (not loading, simply scrolling) through a large webpage smoothly will occur when the second CPU clock rates are no less than 460Mhz. (This is on mine without background tasks taking any CPU. Yours may be different depending on services running, the browser you use, your ROM, kernel, etc.) Thus, the nominal clock rate for scrolling a webpage on my Mi4i is 460Mhz.

To understand what's best under a variety of tasks, we have to identify two types of load profiles: nominal clock rates and efficient clock rates.

Efficient Clock Rates

Efficient clock rates are CPU clock rates that are unique in that they are the most optimal frequency given the range of voltage requirements. If you map out the frequency jump and the voltage requirement jump between each of the available clock rates, you will find that occasionally the voltage requirement will jump significantly without the frequency jumping proportionally to the previous differentials. For example, using stock voltages, the EvoLTE's msm8960 chipset clock/voltage ratios jump significantly higher from 702Mhz to 810Mhz than the ratios from 594Mhz to 702Mhz.

This section is INCOMPLETE! If you know the voltages, please post and I can update this guide to include the Mi4i's Efficient Clock Rates.

Clock Rate Biases

Using the information provided above, figure out both your nominal clock rates for the tasks you perform most often and your efficient clock rates depending on your kernel/custom voltage settings. For me, since I cannot determine the efficient clock rates, I use the nominal clock rates listed above. For the tasks I generally perform on my phone, my nominal clock rates are as follows:

Idle - 345Mhz

Page Scrolling - 533Mhz

Video -800Mhz

App Loading - 960Mhz

High Load Processing - 1612Mhz

(Note that you must calculate the values that are optimal for your phone for best battery and performance! Each phone is different because of the ROM, kernel, background tasks, etc!)

With this done, you will want to start the fine tuning phase! Correlate the efficient clock rates with their closest nominal clock rates, similar to below:

(This section of the guide is INCOMPLETE because I do not know the clock rate voltages for the Mi4i. If you know these, please post in the comments and I will update the guide!)

Idle - ???Mhz efficient / 345Mhz nominal

Page Scrolling - ???Mhz efficient / 533Mhz nominal

Video - ???Mhz efficient / 800Mhz nominal

App Loading - ???Mhz efficient / 960Mhz nominal

High Load - ???Mhz efficient / 1651Mhz nominal

Keep these handy, as they're going to be necessary for...

The Set Up

Now that we know what are the most efficient nominal clock rates we want to focus on and what the most optimal are for what we want to do, we will start low and scale up as necessary. It's always better to begin with underperforming and tweak the settings upward until we're satisfied with the performance of our target tasks.

In its default state, the Interactive governor has a hair trigger that will raise and lower the clock rates, which means it spends too much time at unnecessary clock speeds, wasting power, and scales down too quickly, leading to stuttering performance. We will take advantage of a seldom used feature of the Interactive governor. Specifically, that with which it determines when it is okay to scale up to each higher clock rate, on a frequency by frequency basis.

We have two primary goals: respond as quickly as possible to each load request for a lag free experience and exceed the desired clock rate for a given task as little as possible. To do this, we will instruct the Interactive governor to trigger certain clock rates in different ways depending on our expected load.

I won't explain all of the settings of the Interactive governor--there are plenty of summaries all around. (Go search now if you don't know what any of the settings for Interactive governor do. I'll wait here.) However, I will explain an incredibly powerful feature of the Interactive governor that is rarely included in those summaries: multiple frequency adjustments.

The above_highspeed_delay setting, for example, defines how long the governor should wait before escalating the clock rate beyond what's set in highspeed_freq. However, you can define multiple different delays that the governor should use for any specified frequency.

For example, we want the above_highspeed_delay as low as possible to get the CPU out of the idle state as quickly as possible when a significant load is applied. However, we don't want it to jump immediately to the fastest clock rate once it's gotten out of idle, as that may be overkill for the current task. Our target trigger (which you will later adjust to suit your system and usage profile), will begin at 20000μs. That means 20,000μs (or 20ms) after our idle max load has been reached, we want to assume idle has been broken and we want to perform an actual task. (We want this value as low as possible without false positives, because it is one of a few factors that determine how snappy and lag free the CPU's response is.)

But at this point we're not ready to take on a full processing load. We may just be briefly scrolling a webpage and don't need the full power of the CPU now that we've allowed it to break out of idle. So we need it to reach a particular frequency and then hold it there again until we're sure the load is justified before we allow it to push the frequency even higher. To do that, rather than just setting

above_highspeed_delay - 20000​

we will instead use the format "frequency:delay" to set

above_highspeed_delay - 20000 460000:60000 600000:20000​

"Waaaait... What does that do?!"

This tells the Interactive governor to hold out 20ms after our target load when it's at our highspeed_freq (which we're actually using as our idle frequency--not a burst frequency as originally intended), but then it tells the governor to hold for 60ms after it's reached 460Mhz. Once it has exceeded 460Mhz, it then has free reign to scale up without limitation. (This will be optimized with the target_loads setting in a minute. And if you don't know what I'm talking about when I say "highspeed_freq" then you didn't go search for the basic Interactive governor settings and read about it! Go do that before you read any further, because I will not explain the basics of this governor!)

These settings are among the most important, because they limit the phone's clock rates when you are not interacting with it. If it needs to do something in the background, chances are it does not need to run full throttle! Background and idle tasks should be limited to the lowest reasonable clock rate. Generally speaking, if you're just looking at your phone (to read something, for example), you want the phone to use as little CPU power as possible. This includes checking in with Google to report your location or fetching some pull data or... whatever. Things that you don't need performance for.

So now that we know how to specify different settings for different frequency ranges, let's finish it all up with...

What About Touchboost?

Touchboost is a nifty feature in a lot of kernels (including stock on Mi4i) that jumps up the frequency so that you experience minimal lag. However, with all the above settings, touchboost is usally detrimental to the efficiency of the device!

We generally want to keep the CPU on the lowest possible frequency as much as possible, and touchboost interferes with that. Further, because we've set up the maximal and minimal efficient clock rates, as well as burst processing from the 1st CPU core, we don't need touchboost!

If your kernel allows you to shut it off, try to do so and see if the responsiveness of your device is acceptable. On the Mi4i, touchboost adds no perceptual performance gain and only hurts efficiency and battery life. If your kernel doesn't allow you to turn off touchboost, try another one, like the excellent Sensei;).

Your battery life will thank you!

The Setup

In the "CPU" section, turn off "Touchboost". (This is crucial!! YOU MUST TURN OFF TOUCHBOOST OR ELSE YOU WILL NOT SEE ANY BATTERY SAVINGS!!!) Make sure the "Max CPU Frequency" is set to the maximum possible value for each CPU. Make sure the "Min CPU Frequency" is set to the minimum possible value for each CPU. Under "CPU Boost", set "input boost milliseconds" to "0". Then set the following values for each CPU under "Governor options" for each CPU respectively:

CPU #1 (aka "Big", aka "has 4 cores", aka "maxes out at 1665Mhz")

target_loads - 1 960000:80 1113600:85 1344000:90

timer_slack - 80000

hispeed_freq - 1113600

timer_rate - 20000

above_hispeed_delay - 20000 1113600:50000

go_hispeed_load - 85

min_sample_time - 50000

CPU #2 (aka "little", aka "has 4 cores", aka "maxes out at 1113Mhz")

target_loads - 1 800000:80

timer_slack - 80000

hispeed_freq - 998400

timer_rate - 40000

above_hispeed_delay - 10000

go_hispeed_load - 90

min_sample_time - 40000

The Conclusion

I have achieved unprecedented performance, smoothness, snappiness, and battery life with the default settings I outlined above. However, your mileage may vary, as every phone, ROM, kernel, installed applications, etc are different. This is a very sensitive governor profile and must be tweaked to just meet the requirements of your system and your usage patterns!

If it is not optimally tuned, performance and battery life will suffer! If you're not seeing buttery smooth, snappy performance, you have not correctly tuned it for your system!! However, if you do have superb performance (and you tweaked the values conservatively and not in large steps), then you will also get the aforementioned battery life.

I will be happy to answer any questions, or provide any guidance I can. However:

You must otherwise optimize your phone first! This will not "fix" a poorly optimized system and will, in fact, reduce performance and battery life without further optimization and proper tweaking.

I will not answer questions about "what is a governor?" There are plenty of resources available already, so search for them.

I will not answer questions about "how can I tweak [some other] governor?" This is about the Interactive governor only.

I will not respond to "nuh uh! show proof!" posts. The fact that I spent 12 hours writing this up should be proof enough that I am satisfied with the results. You can take it or leave it; makes no difference to me. The default settings should work with any fully optimized Mi4i running any kernel, so just try them on your own. If you're not absolutely satisfied (and trust me, either it'll work out-of-the-box with flying colors and you'll know it works for your system, or it'll be an awful experience which means you must tweak it), then you haven't adequately adjusted the settings to suit your system.

Lemme know what you think, and good luck!:o

Thanks to [MENTION=5886947]soniCron[/MENTION] for the original thread here : http://xdaforums.com/nexus-5x/general/guide-advanced-interactive-governor-t3269557