[Vibrant Q&A, Help & Troubleshooting] Woody:
ROMs/Kernels, Overclocking/Undervolting and Memory Management

ROMs are key things to think about when it comes to battery life. They can be fully established and working fine, can be RCs and still in development or they can be Alpha/Betas and completely experimental or just beginning. Choosing the best ROM or Kernel is going to depend on what YOU want out of your phone. Do you want a stable 2.2 ROM that has great battery life but not the customizability as MIUI or CM7? Do you want a Gingerbread AOSP ROM that has memory leak issues? There is the rub because CM7 and MIUI have fantastic customization possibilities Gingerbread is well Gingerbread but it has its own issues, and 2.2’s are about as basic as they come. However 2.2’s, because they are so old and overworked, have been Optimized to their fullest and some outstanding tweaks have really brought them to the forefront in daily drivers. Again, the choice is up to you.

Kernels go hand-in-hand with your ROM. Does the kernel support Overclocking or Undervolting. How much RAM and what tweaks are included in the kernel? Does THIS kernel work with THAT ROM? These are all spelled out for you in the OP of each kernel (and ROM) for you to find out. Read them because if you don’t, you’ll bork your phone and then your next post will be, “Help. I Bricked my phone”.

Froyo Kernels (see here) and read their OPs. Many can be Overclocked and some can be Undervolted

Battery Friendly Kernels for MIUI/CM7:

Glitch and Bali-CM (there are others but NOOB_IN_N33D gave me these to put in here). Read their OPs to find out more of what they do.

Overclocking/Undervolting –

If you don’t already know what Overclocking is, well it is pretty much self-explanatory. You can Overclock your CPU above the clock-speed that Samsung, T-Mobile governed it at. This can be done with apps like Tegrak’s Overclock (for stock kernels), SetCPU (here and here), CPUtuner,…Generally have to be ROOTed to do these but if you are flashing ROMs and Kernels then you probably already are. UnderVolting is basically what it sounds like too. You are Undervolting your CPU to conserve battery.

This can be one of the best ways for a more advanced user to save battery. Overclocking is great to see those really cool Quadrant scores. Wow!!! But it also ramps up the battery drain, as well as temperature which can shorten your battery’s TOTAL life. If you want to Overclock to 1.2-1.7 just to see what you score on Quadrant or SmartBench, then do it for that time. Most ROMs/Kernels run stable and smooth at or about 1.0-1.2 with minimal effects on battery (as long as you do tweaks in above post). If you decide to Undervolt you can use Pimp My CPU or Voltage Control to do this but take care to step it down slowly until you find the right settings for you or you will see random reboots or phone freezes and those suck trying to diagnose.

***Please note that whether you Overclock or Undervolt, do NOT “Set on Boot” until you know that they are going to work. Otherwise if it doesn’t work and your phone randomly reboots, you will get into a boot cycle (not a bootloop) because you put them in “Set on Boot”. You must test before you should do this.***

Glitch (Kernel for MIUI/CM7) –very brief overview-See its OP for more

- Up to 1.7GHz CPU OC with added bus/GPU OC (Thanks to morfic for the great base of work)

- Undervolting using Pimp my CPU or Voltage Control

Bali_CM (Kernel for MIUI/CM7) –very brief overview-See its OP for more

- OC/UV up to 1.4GHz (Safe boot to 1GHz) [require SetCPU from market]

- Multiple CPU governor, smartass included (default: ondemand)

- Multiple IO scheduler (default: BFQ)

- CIFS support

- Support SetCPU screen off 100/400 profile

NOOB_IN_N33D is running MIUI and is having great battery life for a 2.3.x ROM. He has given me his settings for Overclocking and Undervolting to put in this guide.

**Please note that these are HIS settings for HIS set-up. They may not work for you but it is a good idea to see what I am talking about when it comes to OC/UV**

N00B_IN_N33D's OC/UV

KaintFM's OC/UV

Memory Management

Did you know that you can also free up some internal memory space by just basic maintenance? You can install a Cache Cleaner from the market. I use Cache Cleaner NG (root) and CacheMate (root) which will clear your cache for you, Cache Cleaner NG will even clear your cache on your SDcard. Open Root Explorer and if you see a bunch of free floating cache files, those need to go. Wasted space. Small in the scheme of your SDcard, but still wasted.

So here we go (best part is at the bottom though):

Ok so you go into XDA on your phone, go to the themes page and look at what and how people are theming their phones or see some pix of someone's SetCPU profiles. All those develop a cache that takes up space on your phone. Now lets say that you go to the market and look through some apps or update your apps (more on this later). This also generates cache, usually up to 2-4mb. Ever try to download something from the market and it says something like "not enough space". This not needed cache may be some of the reason.

Here are some tricks and apps that some of you may know and also some tricks that I have found that I am sure most don't know about.

SOME GOOD LOW MEMORY APPS:

Cache Cleaner NG and Cache Mate (both root and free-Cache Mate has a paid but the free one works just fine.)

Diskusage (free) ~ This one will show you a graphical version of your /data/apps and also you SD card to show you exactly what is taking up so much space. You can click on that item and hit "Show" and it will take you to the app's page in Manager Applications. It also has a root function too that will allow you to see what is in /system, /cache, /data,…

Some sort of file manager to get to some things I'll mention below. (I use Root Explorer)

SOME MEMORY CLEARING TIPS AND TRICKS:

Home Launcher ~ If you have a 3rd party home launcher, see if it has the ability to long-press an icon to take you to its screen in the Manage Apps section. I use ADWex and if you long-press on say Market, it takes me to the same place as is I were to go to Settings->Applications->Manage Apps->Market. Instead of all that, just long-press on the icon and BAM! it takes you there. Here you can clear out your cache for the market or delete the data (if you need to do that). Or clear the cache of the XDA app b/c you looked at too many pix.

Browsers ~ These develop cache that takes up memory and space, especially the stock browser. If you use a 3rd party, you can get the settings to clear cache, cookies, passwords,…on exit. I use Dolphin, but I am pretty sure that most have something like this on them. (side note: most 3rd party browsers once exited will not run in the background unlike the stock one)

Media ~ So you download a bunch of mp3's from the net or click on some pix and save it to your SD card. Or maybe you just felt like wiping your card and having a fresh start. Every time you reboot, you phone will scan media. No big deal, but the more you criss-cross things from PC to phone and back again, it can create a bunch of double files in your media cache on the phone. With the proper placement of .nomedia files (this prevents your media scanner from doing just that, scanning media- i.e. pix, jpegs,…Don’t place a .nomedia in your music, album art or DCIM files**bad).

Every once in a while, I'll hit the Diskusage or go to Manage apps and clear the media cache. Then I got to my file manager and the DCIM->Thumbs and delete the .Thumbnails files (should be 2). Unmount the SD card and remount to start the media scan, pull up the Gallery and wait for the thumbs to come back (depending on how many you have, this could take awhile). By doing this you can get almost 5 mb back if you have a bunch of double scans in your media folder.

AND NOW FOR SOME TIPS THAT MOST COULD NOT KNOW:

LOSTDIR - Lets say that you have your phone plugged into your PC and for some reason you, in a fit of rage, jerk the plug out without unmounting it first. This creates a file that is put into your LOST DIR folder on your SD card. Anytime you don't safely unmount the SD card, it will create a file in that folder. In the scheme of the SD card, it isn't too much, but I don't like having useless items free floating about.

TOMBSTONES - So you are downloading an update from the market and for some reason your phone freezes and the Force Close-Retry-Wait doesn't work out for you. You have to do a battery pull. Frustrating I know and the memory takes a hit too. Every time you have to do a battery pull because of a freeze up or something of the like, it creates a TOMBSTONE file in /data. These are useless and can be deleted. If you are flashing ROMs and are constantly having to do battery pulls b/c market crashes or an app freezes, then you are creating a Tombstone file.

**Here is where your file manager (with root) will help. Go into /data and scroll all the way to the bottom and open /tombstone. There should be some files in there and depending on how many there are, I could be a nice chunk of wasted memory. Just select all and delete. They are not needed. Your internal memory should go up by doing this.

LOST & FOUND - Same scenario, but now go into /data/ cache or /cache and you'll see Dalvik-Cache (don’t mess with this), Lost & Found and Recovery. If you tried to download an app and it got frozen for some reason and had to do a battery pull, the apk will be free floating in there, uninstalled (free floating radical). You can delete this. While it isn't in the Dalvik-Cache folder, it is taking up space. Once you are able to download something completely and correctly from the market, it will populate into Dalvik-Cache correctly and won't be a free radical, as I like to say.

Change Log:

1/23/12 - Added more MIUI OC/UV settings; memory management tips, tricks, apps.

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