An application which manages kernel parameters.
It depends on your kernel which features you can use.
With Kernel Adiutor you can tweak and monitor things like:
CPU (Frequency, Governor)
I/O Scheduler
Kernel Samepage Merging
Low Memory Killer (Minfree settings)
Virtual Memory
Flash/Backup
Build prop Editor
Recovery (Flash, Wipe)
Init.d editor
Saving Profiles
Some settings
CPU Settings:
This is what you're most likely here for, this is the home of Over (and Under) Clocking.GPU Settings:
But it also provides other very useful settings which might not look so simple at first. Here you can select a CPU governor (No guys, I will not list and explain what each one is, there are just too many and too many with stupid names. Instead I will leave you guys with a link to another guide specific about CPU Govs.)
http://androidmodguide.blogspot.co.uk/p/blog-page.html
While we're still talking about CPU Governors, there is a further option that you have if your app supports it. You can tune the specific tunables for each specific Governor, to get the best result possible and most suited to you. Whether you want more performance or battery savings from that specific governor.
Here you can also find toggles for HotPlugging or its counter part CPUquiet (Available only for NVIDIA CPUs I believe.) Hotplugging is simply the technology which decides when and which cores to turn off. CPUquiet is similar but rather than turning off the cores it simply makes the idle. The advantage is debated but the possibility is still there.
This one doesn't have many features (That I know of), it allows you to Over/UnderClock your GPU and also change its Governor.Memory Settings:
(EDIT: I have included a Memory settings after doing a bit more of research about it, since its slightly more complicated compared to the other settings. Although most of these settings are available in both custom or stock kernels they can be tweaked to experience performance and battery improvements. So I'll try to cover as much as I can.)
Here you can tweak anything related to RAM and Cache. For tweaking these settings I suggest using the app Kernel Adiutor which I recommended earlier.
Things which you can find in all kernels are Low Memory Killer (Out of memory killer function on Android.) There is no need for me to explain it, what it does is self explanatory, to better understand the tunables I will provide this link:
http://forum.xda-developers.com/showthread.php?t=622666
You can also find tunables for Virtual Memory (Caching parameters), which is part of "sysctl" in the kernel. Tweaking this improves cache management, helping improve load times of cached apps, battery saving by emptying cache less often etc...
Here is a link which will give you a description for each parameter: https://www.kernel.org/doc/Documentation/sysctl/vm.txt
But there are also things which are not active or part of all kernels. zRAM is part of stock, and some custom kernels disable it. While KSM (Kernel Samepage Merging) can be added by some customs.
zRAM is just compressed RAM space. So you can store more in RAM by compressing the data you can fit more data inside your RAM.
Now obviously it is slower than actual normal RAM (since you have to encrypt and decrypt the data), but apparently it still is faster than using swap (which is in your internal memory rather than RAM). The principle works based on that Android prefers to keep data stored as much as possible in RAM to keep recently used apps running quickly. The more you use an app the more priority it has, therefore will stay in normal RAM, things you use sometimes but not very often are kept in zRAM (regardless of how full your actual RAM is), but since you don't use this very often you don't notice the performance hiccup of decrypting that data.
Then last case scenario things you barely use are kept in swap.
For you IT enthusiasts you should have realised already that "z" is the technology prefix for Compression. So it shouldn't come as a surprise that zRAM is compressed RAM.
KSM (Kernel Samepage Merging), this is simple, but it requires knowledge of some terminology. I will try to explain as simple as possible.
It allows the system to merge/share identical memory pages in RAM from different Applications/Processes. Thus it frees up RAM memory.
The only drawback to this is that it's up to your CPU to perform this task, therefore while it will increase performance it will also use up battery. But this is negligibly small (In my experience).
Therefore my recommendation is that if your Kernel offers this keep it turned on.
