This blog is dead

I just realized I haven't written a new article in years!  Who writes blogs nowadays? :)

twitter: imoseyon

Galaxy Nexus Kernel Features

Been working on Galaxy Nexus kernels almost exclusively for a while. It's not the easiest kernel to work on. The omap4 architecture seems to be very picky about every little change, so I could make a seemingly harmless small mod and BAM the battery drains 2x as fast.

Anyway, I have a Rootzwiki thread, which sees a lot of traffic and I can't usually keep up with the discussions there.  I thought maybe I can use my blogger.com page (which I haven't used in a while) to collect some feature requests from users.  So what about it?  If you'd love to see a feature please post it here.  Keep in mind that I'd probably end up getting to less than 10% of the requests, as this is a "minimalistic" kernel and all. :)  Please try to post feature requests only, all other discussions should go back to the Rootzwiki thread.

CPU Governors

I've been tinkering around with cpu governors quite a bit in my Android kernels.  I believe governors are a single most effective way to improve or diminish the "user perceivable" performance of the device.


Here's my personal take on governors that are included in stock and other custom kernels:


performance - max speed all the time
powersave - lowest speed all the time
conservative - slow ramp-up

The next few get a bit more complex. ondemand, interactive, and smartass all try to pretty much do the same thing: perform well and power efficient. But the way they approach their goals are very different (ie. their algorithms are very different).

1) ondemand - been in linux for a long time and we got really smart linux kernel developers working on it and the code gets reviewed by really smart people. At the same time this governor is really designed to work on desktops, servers, phones, etc - a universal solution.
2) interactive - developed by CM (I think), tuned for performance. Instead of sampling at every interval like ondemand, it determines how to scale up when cpu comes out of idle.
3) smartass - developed by erasmux for his android kernel. Popular for its ability to use android's onboard suspend mechanism to keep the phone below a certain clock speed when screen is turned off. Also does slow ramp-up like the conservative governor.

Instead of the above, here are the three governors that I include in my custom kernels:

• interactiveX - it's the interactive governor from CM, but I added suspend/wake logic so when the phone screen is off it runs at below 400Mhz. Also, I modified its code some more to minimize unnecessary cpu spikes above a certain threshold if kernel is heavily overclocked. (Most devices are unstable above a certain speed when it's heavily overclocked, and it's the quick jump to top speed that usually locks up the phone.)
  I like this governor because it's simple and fast.
• ondemandX - ondemand governor code from latest linux (3.0 at the moment) source *plus* the suspend/wake logic described above. No further optimization is done.
• smartass - smartass code from erasmux, but I wasn't happy with its performance so I tuned it for quicker ramp up in speed. It has the same suspend/wake logic as ondemandX, and similar stability optimizations as interactiveX. (update: smartassV2 is new and currently I include the v2 in my kernels without optimizing further).

Kernels

Building kernels has been my thing lately.  Been developing for:

• Thunderbolt
• Droid Charge
• Samsung Fascinate/Mesmerize/Showcase
• Samsung Galaxy Tab 7"

You can find my threads on http://rootzwiki.com/.

DX/D2 tweaks new version (man it's been a while)

Sorry guys, I've been pretty busy developing kernels for thunderbolt in the recent weeks in my spare time. Which i don't have a lot of due to a full time job (in case someone from work is reading this). ;)

Here's an updated zip for DX/D2 users.  If you're already on thunderbolt, you shouldn't have to flash this zip (although it won't fail) - you should be flashing my kernels instead!  If you're on someone else's kernel and flashing this zip to get my tweaks shame on you! :-)

v7.1 (download)

To verify that all the tweaks are in place:

1. Open Terminal Emulator
2. su
3. checktweak.sh

 CHANGELOGS
v7.1

1. Latest busybox compiled by yours truly.
2. Modified enable scripts to work on GB ROMs.
3. Easier to run check script (see above).
4. SD card speed boost.

NOTE: the latest version has been tested on Gingerbread only.  Should work fine on Froyo but hasn't been tested. Also, if you're running ZombieStomped there's no need to flash.

NOTE to D1 users: Been working with Liquid to develop kernels for D1 as well.  Still work in progress.

Not so universal for original Droid

I was recently approached by Jason at Droidforums to see if I can make a zip for my tweaks for Droid 1.  Working with him closely (since I don't have a D1) I was able to come up with a slightly crippled version of my mods for Droid 1 running Project Elite ROM (but it should work for any ROMs that have init.d support).

Download

To check to see if the mods are working: open Terminal Emulator and type "bash /system/etc/imoseyon/checkimosey.sh" without quotes.

I'll try my best to further enhance the mods but I'll need some help from other D1 users. :)

minimal kernel for tbolt

Been messing with compiling kernels for my thunderbolt.  You can read about it here: http://goo.gl/hmhyb

More details on this later.  Combing through the kernel code for more tweaking opportunities. ;)