Database Users

[Q] [REQ] Galbraith Patch worked into kernals?

http://www.pcworld.com/businesscent...x_kernel_patch_delivers_huge_speed_boost.html
http://forum.xda-developers.com/showthread.php?t=844458
could this be worked into Epic 4G kernels as well?

tyl3rdurden said:
http://www.pcworld.com/businesscent...x_kernel_patch_delivers_huge_speed_boost.html
http://forum.xda-developers.com/showthread.php?t=844458
could this be worked into Epic 4G kernels as well?
Click to expand...
Click to collapse
WOW. I am seriously impressed by your "keeping up with the times" mentality. Good job on noticing this!
So...
"n tests by Galbraith, the patch reportedly produced a drop in the maximum latency of more than 10 times and in the average latency of the desktop by about 60 times. Though the merge window is now closed for the Linux 2.6.37 kernel, the new patch should make it into version 2.6.38."
Along with an Overclocked Froyo kernel (once source is out) this should REALLY improve our experiences.
I mentioned in another thread that I am in talks with Paragon software
http://www.paragon-software.com/exp...ocs/technologies/Paragon_UFSD_for_Android.pdf
for NTFS and HSF access. I think that is is POSSIBLE that this is actually a software patch, although it may need to be placed into the kernel itself as a driver. I promise to update as soon as they get back to me as I just spoke to the devs there yesterday.
Looks like our experience is about to improve dramatically!

Already in IntersectRavens latest kernel and wildmonk's latest beta kernels for nexus one. Check the threads
Click to expand...
Click to collapse
From the other xda thread someone mentioned that some kernels have already implemented. I am sure some of them would be glad to share how it is implemented and how easily it can be done. I know it is different phones/kernels but the idea behind it should be similar.

Dulanic said:
From the other xda thread someone mentioned that some kernels have already implemented. I am sure some of them would be glad to share how it is implemented and how easily it can be done. I know it is different phones/kernels but the idea behind it should be similar.
Click to expand...
Click to collapse
We don't have a source kernel for Froyo yet to do this. Someone correct me if I am wrong please.
Edit: I can't find anything mentioning this patch. If anyone has a link post it. I don't believe this is implemented anywhere yet.

I found the below info here:
http://www.reseize.com/2010/11/linux-kernel-patch-that-does-wonders.html
Below is the video of the Linux desktop when running the kernel and the patch in question was applied but but disabled:
As you can see, the experience when compiling the Linux kernel with so many jobs is rather troubling to the Linux desktop experience. At no point in the video was the 1080p sample video paused, but that was just where the current mainline Linux kernel is at with 2.6.37. There was also some stuttering with glxgears and some responsiveness elsewhere. This is even with all of the Linux 2.6.37 kernel improvements up to today. If recording a video of an older kernel release, the experience is even more horrific! Now let's see what happens when enabling the patch's new scheduler code
It is truly a night and day difference. The 1080p Ogg video now played smoothly a majority of the time when still compiling the Linux kernel with 64 jobs. Glxgears was also better and the window movements and desktop interactivity was far better. When compiling the Linux kernel with 128 jobs or other workloads that apply even greater strain, the results are even more dramatic, but it is not great for a video demonstration; the first video recorded under greater strained made the "before look" appear as like a still photograph.

This could be potentially patched into our Eclair kernel if the changes aren't too intrusive, and by the sounds of it they're not.
The mainline patch was against 2.6.39 kernel however, our froyo kernel will be 2.6.32 and eclair is 2.6.29 - so we're several revisions behind in eclair.
It's definitely interesting, but it's geared toward desktops using the group scheduler - absolutely worth a try if that scheduler works with android easily ( most of the community kernels are using BFS scheduler however )

cicada said:
This could be potentially patched into our Eclair kernel if the changes aren't too intrusive, and by the sounds of it they're not.
The mainline patch was against 2.6.39 kernel however, our froyo kernel will be 2.6.32 and eclair is 2.6.29 - so we're several revisions behind in eclair.
It's definitely interesting, but it's geared toward desktops using the group scheduler - absolutely worth a try if that scheduler works with android easily ( most of the community kernels are using BFS scheduler however )
Click to expand...
Click to collapse
Sniff...
It did sound a little too good to be true. Well, eventually we will get 2.6.38 and that has it built in, if the desktop group scheduler can even be used at all it seems.

but because its in other peoples' kernels cant it be easily ported into ours?

tyl3rdurden said:
but because its in other peoples' kernels cant it be easily ported into ours?
Click to expand...
Click to collapse
It's very possible to patch in. If it's been done before, anyway.
But, because it is based on the .39 kernel, it might be a little buggy. Or a lot buggy. You wanna link me to a kernel that has it and I'll look into it? I probably will wait for Froyo source for at least the .32 kernel.

Here's what Linus himself had to say about the patch:
Yeah. And I have to say that I'm (very happily) surprised by just how small that patch really ends up being, and how it's not intrusive or ugly either.
I'm also very happy with just what it does to interactive performance. Admittedly, my "testcase" is really trivial (reading email in a web-browser, scrolling around a bit, while doing a "make -j64" on the kernel at the same time), but it's a test-case that is very relevant for me. And it is a _huge_ improvement.
It's an improvement for things like smooth scrolling around, but what I found more interesting was how it seems to really make web pages load a lot faster. Maybe it shouldn't have been surprising, but I always associated that with network performance. But there's clearly enough of a CPU load when loading a new web page that if you have a load average of 50+ at the same time, you _will_ be starved for CPU in the loading process, and probably won't get all the http requests out quickly enough.
So I think this is firmly one of those "real improvement" patches. Good job. Group scheduling goes from "useful for some specific server loads" to "that's a killer feature".
Click to expand...
Click to collapse

DevinXtreme said:
It's very possible to patch in. If it's been done before, anyway.
But, because it is based on the .39 kernel, it might be a little buggy. Or a lot buggy. You wanna link me to a kernel that has it and I'll look into it? I probably will wait for Froyo source for at least the .32 kernel.
Click to expand...
Click to collapse
Devin- I agree with waiting until the Froyo source is out for attempting to implement this. I'm not sure that group scheduling is even an option in the Android kernel. But I don't think anyone has done this so I doubt any links are coming your way.
Edit: Found this here- http://groups.google.com/group/android-kernel/browse_thread/thread/f47d9d4f4e6a116a/ab1a8ab42bb0b84a
Android is using the CFS.
They are combine with RT scheduling.
When you playing the audio and video service, paltform change the
scheduling policy and change the schedule prority.
search the platform code
dalvik has policy n proiorty setting code, also framework related with
audio n video
check the init.rc and cutil folder
u need to search the platform after eclair release (Froyo)

cicada said:
( most of the community kernels are using BFS scheduler however )
Click to expand...
Click to collapse
Actually, no Epic kernel uses BFS. It isn't stable on our hardware, and its not worth porting. Android uses CFS by default, and then the CFQ scheduler I think, but most have switched from CFS/CFQ to CFS/BFQ combination. I know mine & Devin's kernels have.

Geniusdog254 said:
Actually, no Epic kernel uses BFS. It isn't stable on our hardware, and its not worth porting. Android uses CFS by default, and then the CFQ scheduler I think, but most have switched from CFS/CFQ to CFS/BFQ combination. I know mine & Devin's kernels have.
Click to expand...
Click to collapse
Ok then, so in your professional opinion is this patch a possibility still?

Enter your search termsSubmit search formWeblkml.org
Subject [RFC/RFT PATCH] sched: automated per tty task groups
From Mike Galbraith <>
Date Tue, 19 Oct 2010 11:16:04 +0200
Greetings,
Comments, suggestions etc highly welcome.
This patch implements an idea from Linus, to automatically create task groups
per tty, to improve desktop interactivity under hefty load such as kbuild. The
feature is enabled from boot by default, The default setting can be changed via
the boot option ttysched=0, and can be can be turned on or off on the fly via
echo [01] > /proc/sys/kernel/sched_tty_sched_enabled.
Link to code: http://forums.opensuse.org/english/...ernel-speed-up-patch-file-mike-galbraith.html

Thanks for the clarification Geniusdog254.
ZenInsight, any chance you can prune down that post and just use a link? The patch is all over the web right now, and it's hard to scroll by on a phone

ZenInsight said:
Ok then, so in your professional opinion is this patch a possibility still?
Click to expand...
Click to collapse
I'm sure its possible, I just haven't looked at it yet. Like I stated before, until we get 2.6.32 FroYo kernel source I'm not doing any devving besides app work (maybe)
EDIT: Devin said on the last page that he'll look into it. I know IntersectRavens Nexus kernel has it, but I haven't looked into any reports of how much it helps.

Also found this:
Phoronix recently published an article regarding a ~200 lines Linux Kernel patch that improves responsiveness under system strain. Well, Lennart Poettering, a RedHat developer replied to Linus Torvalds on a maling list with an alternative to this patch that does the same thing yet all you have to do is run 2 commands and paste 4 lines in your ~/.bashrc file. I know it sounds unbelievable, but apparently someone even ran some tests which prove that Lennart's solution works. Read on!
Lennart explains you have to add this to your ~/.bashrc file (important: this won't work on Ubuntu. See instructions for Ubuntu further down the post!):
CODE:
if [ "$PS1" ] ; then
mkdir -m 0700 /sys/fs/cgroup/cpu/user/$$
echo $$ > /sys/fs/cgroup/cpu/user/$$/tasks
fi
Linux terminal:
mount -t cgroup cgroup /sys/fs/cgroup/cpu -o cpu
mkdir -m 0777 /sys/fs/cgroup/cpu/user
Further more, a reply to Lennart's email states that his approach is actually better then the actual Kernel patch:
I've done some tests and the result is that Lennart's approach seems to work best. It also _feels_ better interactively compared to the vanilla kernel and in-kernel cgrougs on my machine. Also it's really nice to have an interface to actually see what is going on. With the kernel patch you're totally in the dark about what is going on right now.
-Markus Trippelsdorf
The reply also includes some benchmarks you can see @ http://lkml.org/lkml/2010/11/16/392
Found all this here (Ubuntu patch info too):
http://www.webupd8.org/2010/11/alternative-to-200-lines-kernel-patch.html

JIT on galaxy s

Recently, I finished finally modifying the xperia x10 that I have and one of the greatest improvements that those guys achieved was getting a lot more processing power by enabling JIT.
So naturally after seeing it work miracles on the x10, I went to look for it on my captivate and so far have come up with nothing anywhere. I saw some discussion in the past about it but nothing beyond.
Hopefully somebody can enlighten and if such a thing does seriously want to be worked on.... Here's a thread!
Sent from my GT-I9000 using Tapatalk

FroYo (2.2) and later have Just-In-Time compilation (JIT) out of the box. There are probably a dozen FroYo ROMs on the front page alone, so pick one have fun!

From what I've read, it's been a part of the ROMs since 2.1 but it needs to be enabled. Is this the case here or am I missing something?
Sent from my GT-I9000 using Tapatalk

kr3w1337 said:
From what I've read, it's been a part of the ROMs since 2.1 but it needs to be enabled. Is this the case here or am I missing something?
Sent from my GT-I9000 using Tapatalk
Click to expand...
Click to collapse
That is one of the biggest parts of froyo is that it enables JIT...so if you run a rom that has froyo its enabled unless I'm mistaken...
Sent from my GT-I9000 using XDA App

JIT is enabled by default in all Froyo ROM's. You can check the build.prop for ****s and giggles though.
The Galaxy S won't show the kinds of scores that Qualcomm based devices will, even with JIT enabled. Qualcomm included 128-bit SIMD Floating Point extensions with Snapdragon, while the Hummingbird only has 64-bit extensions.

yes with jit we get a 60-70% improvement but a qualcom gets 300%+ in floating point operation. in modern computers there are many other factors though and quardrant cpu scores are still very high for our chip (if you use the pay version you can see the score breakdown). so dont let the linpack scores discorage you. ive gotten as high as 18.2 in linpack with some overclocking though, which isn't bad. it's not the 50+ in the qualcom phones with some mods but not bad.

So that's what the story is, thanks guys! Wondering if things could be improved beyond overclocking...

I know it can be but don't know how. Some guys are getting 25+ in linpack on there website. So there is something else holding us back a bit.
Sent from my SAMSUNG-SGH-I897 using Tapatalk

Dani897 said:
I know it can be but don't know how. Some guys are getting 25+ in linpack on there website. So there is something else holding us back a bit.
Sent from my SAMSUNG-SGH-I897 using Tapatalk
Click to expand...
Click to collapse
You talking about xperia x10? really 25 on linpack? I dunno if that is even possible to OC to astronomical speeds. They run on older hardware and I think most are still on 2.1.....

All Android ROMs have a JIT compiler, it literally is what compiles all the Java on the fly. Newer versions are optimized for better performance.
So the better question is do the 2.2 Froyo ROMs have the latest JIT compiler version available or does the Nexus S have a newer more performant version we can steal. More than likely it will not work with 2.2 since the Nexus S is using 2.3.
From everything I have heard the newer JIT comp versions are optimized for the Snapdragon chipset more than anything. Which doesn't do us much good.

2.2+ have the JIT. Prior to 2.2, all programs ran entirely as interpreted bytecode on an isolated virtual machine. In 2.2+, the JIT translates the most cpu "heavy" bytecode down to native instructions during execution, stores it in cache, then runs it natively on the processor in a protected mode. Dig the video below, it's an hour long but the functionality of the JIT is explained in the first 15 minutes.
^Edited the above to accurately describe the function of the JIT
http://www.youtube.com/watch?v=Ls0tM-c4Vfo There you go, dudes. JIT Demystified.

modest_mandroid said:
2.2+ have the JIT. Prior to 2.2, all programs ran as bytecode on an isolated virtual machine. In 2.2+, the JIT translates the bytecode down to native instructions just before execution, then runs it natively on the processor in a protected mode. Could be wrong, but to my understanding, that is the major difference between 2.1- and 2.2+.
http://www.youtube.com/watch?v=Ls0tM-c4Vfo There you go, dudes. JIT Demystified.
Click to expand...
Click to collapse
This is what I saw and know too. However, I believe that the compiler that we are using is rather old and has some room for improvement. The nexus S compiler working on the captivate is a possibility that could become true after the 2.3 port is finished, provided that the developers look into it.
Sent from my GT-I9000 using Tapatalk

Question: Making a EC05 kernel

How hard would it be to make a EC05 kernel that has EXT4 support, Undervolted, Dual boot support, increased FPS to 75. I don't want/need overclocking ability.

Question 1, why not just use Genocide? Question 2, why the fps increase?
But if you were to make your own, you might want to find a guide for compiling your own kernel from source.
Also, this would've probably been better in Development or Q & A

ugothakd said:
Question 1, why not just use Genocide? Question 2, why the fps increase?
But if you were to make your own, you might want to find a guide for compiling your own kernel from source.
Also, this would've probably been better in Development or Q & A
Click to expand...
Click to collapse
Oh I didn't know there was a Development Q&A forum and yes it would be better in that forum. I used Genocide and the battery life I get with that Kernel wasn't great. Currently I'm using revolt kernel and the battery life seems decent but I would like to dual boot because I'm currently creating my own EC05 rom. The FPS increase is just a + for some games I play I usually aim for 60+ on my computer might aswell aim for 60+ on my phone. I'm pretty sure the PowerVR SGX540 could run most android games at 60+ without an issue at 480x800
Edit: just noticed Twilight Zone kernel has been updated, I haven't used it since v1.0 and I wasn't pleased with the battery performance. Still wish it had dual boot support.

I'm on era and I haven't ever used dial boot but I'm pretty sure our revolt kernel is capable, at least that was the idea when we first created it. I could be wrong but and may have missed an update where we took that capability out, but like I said I think it supports dual boot. I will try and get into contact with our kernel guys and double check for you.
Sent from my GT-P7510 using xda premium

newbieandroid said:
Oh I didn't know there was a Development Q&A forum and yes it would be better in that forum. I used Genocide and the battery life I get with that Kernel wasn't great. Currently I'm using revolt kernel and the battery life seems decent but I would like to dual boot because I'm currently creating my own EC05 rom. The FPS increase is just a + for some games I play I usually aim for 60+ on my computer might aswell aim for 60+ on my phone. I'm pretty sure the PowerVR SGX540 could run most android games at 60+ without an issue at 480x800
Edit: just noticed Twilight Zone kernel has been updated, I haven't used it since v1.0 and I wasn't pleased with the battery performance. Still wish it had dual boot support.
Click to expand...
Click to collapse
The fps patch I know nothing about, so I can't help you there. As for the dual boot, I contacted the creator of it (Rodderik) on irc and he said to take the initramfs files and overwrite them in the kernel's initramfs. For that, you would need to unpack/repack the initramfs. Chris41g has a tutorial. Once you get that done, you should setup your dualboot sdcard.

stormglove said:
I'm on era and I haven't ever used dial boot but I'm pretty sure our revolt kernel is capable, at least that was the idea when we first created it. I could be wrong but and may have missed an update where we took that capability out, but like I said I think it supports dual boot. I will try and get into contact with our kernel guys and double check for you.
Sent from my GT-P7510 using xda premium
Click to expand...
Click to collapse
Thank you very much, so far I'm liking the kernel's battery life. It would be awesome if it could dual boot.

[REF] Memory Allocator Benchmark

This one will be of more interest to kernel developers.
Link to Spreadsheet: Results
RcrdBrt asked me to see which memory allocator performed best, and provided me with four identical kernels except for the allocators being SLQB, SLAB, SLUB, and SLOB.
SLUB turns out to have a slight performance advantage, as RcrdBrt had suspected.
The rank was:
SLUB - 980.56
SLQB - 972.17
SLAB - 967.72
SLOB - 967.72
Not much difference really, but every little helps, as they say at Tesco (Britain's leading super market/Religion).
Thanks to RcrdBrt for trusting me with this nice little study, and to Chainfire for the very useful benchmarking app. (See here)
Methodology
Technical detail (it's not necessary to read this!)
I used CF-Bench to obtain values for:
Native MALLOCS
Native Mem Read
Native Mem Write
Java Mem Read
Java Mem Write
...and used statistical methods to boil 10 passes for each allocator down to one final score: 10 passes is enough to get the mean and median within one percent of each other, i.e. establishes a confidence in the mean, assuming normally distributed data. Three standard deviations are subtracted from the mean, to show the minimum score we'd expect 99.7% of results to be above. This is to penalize variability (high peaks are less significant than a good consistency). The geometric mean is taken of the five end results to provide one final score.

Bedalus can't live without benchmarks. Closed UX benchmark yesterday and opened a new one today
One more instructive and helpful benchmark buddy

Most kernel developers prefer using SLQB. Any thoughts on why this is the case? Do they have a special reason for that or just a matter of not knowing better? Cheers!

RcrdBrt said it was the fashion! Tbh i don't know the differences between them, but some casual googling showed that slub has had success in other Linux arenas

apatal said:
Most kernel developers prefer using SLQB. Any thoughts on why this is the case? Do they have a special reason for that or just a matter of not knowing better? Cheers!
Click to expand...
Click to collapse
Buzzwordism. The other 3 are in kernel.
Sent from my Nexus Prime.

morfic said:
Buzzwordism. The other 3 are in kernel.
Click to expand...
Click to collapse
You mean all those allocators are present but they mention only SLQB because it's the trend?
Sent from my Nexus S

apatal said:
You mean all those allocators are present but they mention only SLQB because it's the trend?
Sent from my Nexus S
Click to expand...
Click to collapse
Correct.
Sent from my Nexus Prime.

Man, bedalus is really fast!
@morfic:
So, in the ICS stock 3.0.8 kernel, how many and which allocators are present?
Am I correct to say that all those four allocators are present, but only one is used?
Sorry for these dumb questions.

glennkaonang said:
Man, bedalus is really fast!
@morfic:
So, in the ICS stock 3.0.8 kernel, how many and which allocators are present?
Am I correct to say that all those four allocators are present, but only one is used?
Click to expand...
Click to collapse
SLAB, SLUB, SLOB are in most (mainline) Linux Kernel, SLQB is patched in.

bedalus, did you run this on GB too?

morfic said:
bedalus, did you run this on GB too?
Click to expand...
Click to collapse
I can do it if i have 4 identical gb kernels (except for the allocator) ... If you'd like it testing you'll have to build them for me?

[Newbie] Kernels (what are they?) :p

Hello guys. I'm a noob and i want to learn xD
I guess this is what XDA is all about
Would Someone explain what a kernel really is?
I know its the backend of the phone that processes.
The question is what do the custom kernels do?
What's different than the stock kernel ?
Waiting for an answer
Thanks
Sent from my GT-S5360 using xda app-developers app

Kernel is the commander of phone..
Btw stock kernel is limited it has deafult features like- 2 cpu frequency,no i/o scheduler some governors.
And in other hands custom kernel has lot more features like many cpu frequency to chose,many cpu governors,i/o scheduler,init.d support for using tweak. They are bettery saver.. There is some custom kernel which can also overclock your cpu.. Like merruk 2.5 kernel is 1.25 GHZ!!!!
there is more fetures in a custom kernel than stock kernel..
custom kernel has too many benifits btw...
some custom kernels-
White kernel
Merruk kernel
Savie kernel
Kuro kernel
Hells_fusion
Repencis kernel

So that means if i install a custom kernel it will overclock my processor....?
Sent from my GT-S5360 using xda app-developers app

as of now only merruk can overclock ur proccessor...
U..Y U NO PRESS THAT THANKS BUTTON IF I HELPED U >.<

prashantj95 said:
So that means if i install a custom kernel it will overclock my processor....?
Sent from my GT-S5360 using xda app-developers app
Click to expand...
Click to collapse
Not really we don't have true over clock yet - but you can try merruk !
Customs Kernels are lot more than being able to change min and max frequencies the thing is i don't have much know how so I'll leave it to any other knowledgeable person reading this thread to answer you precisely
By the way you could have found all that you wanted and even more by spending a minute or two searching no offense
a plus b the whole square is equal to a square plus two ab plus b square

nikufellow said:
Not really we don't have true over clock yet - but you can try merruk !
Customs Kernels are lot more than being able to change min and max frequencies the thing is i don't have much know how so I'll leave it to any other knowledgeable person reading this thread to answer you precisely
By the way you could have found all that you wanted and even more by spending a minute or two searching no offense
a plus b the whole square is equal to a square plus two ab plus b square
Click to expand...
Click to collapse
This XDA app isn't very user friendly
X(
Search doesn't work for me.
Sent from my GT-S5360 using xda app-developers app

Xda is about open-source knowledge sharing,
Basically a kernel is the one that tells your device what to do and what are process needed to execute it
--------------------------------------------------------------
By staring at this post you have waived your right to privacy
Complaints will be trolled accordingly

prashantj95 said:
This XDA app isn't very user friendly
X(
Search doesn't work for me.
Sent from my GT-S5360 using xda app-developers app
Click to expand...
Click to collapse
No problem i was just saying
a plus b the whole square is equal to a square plus two ab plus b square

u want tol learn xda...
then learn the first thing..
when someone helps u...
press thanx button...
**rooting is new for me...and i am noob to root...**

nikufellow said:
Not really we don't have true over clock yet - but you can try merruk !
Click to expand...
Click to collapse
Overclock works. Not perfectly but works obviously.. Even the 900mhz overclocked kernel by merruk works for me.. U can feel it when your phone become warmer..

prashantj95 said:
So that means if i install a custom kernel it will overclock my processor....?
Sent from my GT-S5360 using xda app-developers app
Click to expand...
Click to collapse
Just put Samsung galaxy y s5360 in front of all your searches
_____________________________________
This post uses the patented TingTingin®™ method I would teach it to you but you are not yet worthy (come back in a hundred years)

Basically if i would have to explain what kernel is all about..
Den i would say,
If ur smartfone is a Mercedes then ur kernel is engine.!
Lol
Sent from my GT-S6102 using xda premium

What is a kernel? If you spend any
time reading Android forums,
blogs, how-to posts or online
discussion you'll soon hear people
talking about the kernel. A kernel
isn't something unique to Android
-- iOS and MacOS have one,
Windows has one, BlackBerry's
QNX has one, in fact all high level
operating systems have one. The
one we're interested in is Linux, as
it's the one Android uses. Let's try
to break down what it is and what
it does.
Android devices use the Linux
kernel, but it's not the exact same
kernel other Linux-based
operating systems use. There's a
lot of Android specific code built
in, and Google's Android kernel
maintainers have their work cut
out for them. OEMs have to
contribute as well, because they
need to develop hardware drivers
for the parts they're using for the
kernel version they're using. This
is why it takes a while for
independent Android developers
and hackers to port new versions
to older devices and get
everything working. Drivers
written to work with the
Gingerbread kernel on a phone
won't necessarily work with the Ice
Cream Sandwich kernel. And
that's important, because one of
the kernel's main functions is to
control the hardware. It's a whole
lot of source code, with more
options while building it than you
can imagine, but in the end it's
just the intermediary between the
hardware and the software.
When software needs the
hardware to do anything, it sends
a request to the kernel. And when
we say anything , we mean anything.
From the brightness of the
screen, to the volume level, to
initiating a call through the radio,
even what's drawn on the display
is ultimately controlled by the
kernel. For example -- when you
tap the search button on your
phone, you tell the software to
open the search application. What
happens is that you touched a
certain point on the digitizer,
which tells the software that
you've touched the screen at
those coordinates. The software
knows that when that particular
spot is touched, the search dialog
is supposed to open. The kernel
is what tells the digitizer to look
(or listen, events are "listened"
for) for touches, helps figure out
where you touched, and tells the
system you touched it. In turn,
when the system receives a touch
event at a specific point from the
kernel (through the driver) it
knows what to draw on your
screen. Both the hardware and
the software communicate both
ways with the kernel, and that's
how your phone knows when to do
something. Input from one side is
sent as output to the other,
whether it's you playing Angry
Birds, or connecting to your car's
Bluetooth.
It sounds complicated, and it is.
But it's also pretty standard
computer logic -- there's an action
of some sort generated for every
event. Without the kernel to
accept and send information,
developers would have to write
code for every single event for
every single piece of hardware in
your device. With the kernel, all
they have to do is communicate
with it through the Android system
API's, and hardware developers
only have to make the device
hardware communicate with the
kernel. The good thing is that you
don't need to know exactly how or
why the kernel does what it does,
just understanding that it's the
go-between from software to
hardware gives you a pretty good
grasp of what's happening under
the glass. Sort of gives a whole
new outlook towards those fellows
who stay up all night to work on
kernels for your phone, doesn't
it?
:screwy:
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Cool.yash17 said:
What is a kernel? If you spend any
time reading Android forums,
blogs, how-to posts or online
discussion you'll soon hear people
talking about the kernel. A kernel
isn't something unique to Android
-- iOS and MacOS have one,
Windows has one, BlackBerry's
QNX has one, in fact all high level
operating systems have one. The
one we're interested in is Linux, as
it's the one Android uses. Let's try
to break down what it is and what
it does.
Android devices use the Linux
kernel, but it's not the exact same
kernel other Linux-based
operating systems use. There's a
lot of Android specific code built
in, and Google's Android kernel
maintainers have their work cut
out for them. OEMs have to
contribute as well, because they
need to develop hardware drivers
for the parts they're using for the
kernel version they're using. This
is why it takes a while for
independent Android developers
and hackers to port new versions
to older devices and get
everything working. Drivers
written to work with the
Gingerbread kernel on a phone
won't necessarily work with the Ice
Cream Sandwich kernel. And
that's important, because one of
the kernel's main functions is to
control the hardware. It's a whole
lot of source code, with more
options while building it than you
can imagine, but in the end it's
just the intermediary between the
hardware and the software.
When software needs the
hardware to do anything, it sends
a request to the kernel. And when
we say anything , we mean anything.
From the brightness of the
screen, to the volume level, to
initiating a call through the radio,
even what's drawn on the display
is ultimately controlled by the
kernel. For example -- when you
tap the search button on your
phone, you tell the software to
open the search application. What
happens is that you touched a
certain point on the digitizer,
which tells the software that
you've touched the screen at
those coordinates. The software
knows that when that particular
spot is touched, the search dialog
is supposed to open. The kernel
is what tells the digitizer to look
(or listen, events are "listened"
for) for touches, helps figure out
where you touched, and tells the
system you touched it. In turn,
when the system receives a touch
event at a specific point from the
kernel (through the driver) it
knows what to draw on your
screen. Both the hardware and
the software communicate both
ways with the kernel, and that's
how your phone knows when to do
something. Input from one side is
sent as output to the other,
whether it's you playing Angry
Birds, or connecting to your car's
Bluetooth.
It sounds complicated, and it is.
But it's also pretty standard
computer logic -- there's an action
of some sort generated for every
event. Without the kernel to
accept and send information,
developers would have to write
code for every single event for
every single piece of hardware in
your device. With the kernel, all
they have to do is communicate
with it through the Android system
API's, and hardware developers
only have to make the device
hardware communicate with the
kernel. The good thing is that you
don't need to know exactly how or
why the kernel does what it does,
just understanding that it's the
go-between from software to
hardware gives you a pretty good
grasp of what's happening under
the glass. Sort of gives a whole
new outlook towards those fellows
who stay up all night to work on
kernels for your phone, doesn't
it?
:screwy:
Sent from my GT-S5360 using xda app-developers app
Click to expand...
Click to collapse
So it's basically divides the software developer and hardware developer's work.
One more question though.
If my hardware is limited., assuming OEMs made a driver for every hardware, what do these custom kernels offer, different from OEMs kernel.
Thanks for the help bro.
Sent from my GT-S5360 using xda app-developers app

Dude Custom kernels
Help You In Power Consumption
Overclocking .
More Perfomane Etc
Dont Forget To Press Thanks
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this is the best answer evah!
CLICK HERE

prashantj95 said:
So that means if i install a custom kernel it will overclock my processor....?
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Click to expand...
Click to collapse
means u can increase frequencies from 832mhz upto 1.2ghz but it will consume more battry