Make the CPU higher efficiency

[richy1989]

Hi,it's a new new discovery for the Kindle.
For instance, the indexer can waste almost 100% of the CPU time when it is running.
For to release the CPU,
we can reduce using the CPU by make a change.

There are many ' *.jar ' in the directory of /usr/java/bin/cvm

just like:
*de_DE.jar
*es_ES.jar
*fr_FR.jar
*it_IT.jar
*ja_JP.jar
*pt_BR.jar

they always working when our Kindle is running,but we don't use it if we are reading the 'local language‘ document.

Then I found something useful in the file /etc/upstart/framework
there is a line said
'JAR_LIST=$(find $EHOME/lib $EHOME/booklet /usr/local/ebook/lib /opt/amazon/pkg/oss/lib -name \*.jar 2>/dev/null) '

So we can backup the files and remove it from our device for to prevent them from running.

Here is the main steps:
------------------------------------------------------------------
1.Install the Jailbreak and usbnetwork

2.Use the Winscp to make a ssh to the Kindle

3.Run the script:

#!/bin/sh

/etc/upstart/framework stop

cd /opt/amazon/ebook/lib
mkdir -p /mnt/us/.backup/opt/amazon/ebook/lib

mv *de_DE.jar /mnt/us/.backup/opt/amazon/ebook/lib/
mv *es_ES.jar /mnt/us/.backup/opt/amazon/ebook/lib/
mv *fr_FR.jar /mnt/us/.backup/opt/amazon/ebook/lib/
mv *it_IT.jar /mnt/us/.backup/opt/amazon/ebook/lib/
mv *ja_JP.jar /mnt/us/.backup/opt/amazon/ebook/lib/
mv *pt_BR.jar /mnt/us/.backup/opt/amazon/ebook/lib/

/etc/upstart/framework start

sync
sync
sync
reboot

4.Restart the Kindle.

----------------------------------------------------------------------

Tips:Chose the right files ’*.jar'!!!!!!!!!
Example:If your local language is Japannes,
you will have to keep the file '*ja_JP.jar' from being deleted!!!!!


Here are the situation of CPU after finished all the step above.

Before operation





After operation




It's test Successfuly for Paperwhite

[NiLuJe]

Apples vs. oranges.

You're comparing a snapshot from a point in time where the framework is doing background tasks (catalog/cleanup/scan/indexing) [mostly from some of the niced threads, hence most of the CPU usage falling in the 'nice' column], to one where it isn't.

That's not even taking into account that the CPU frequency is variable, so, depending on which state the CPU governor thought the CPU should be in, top's percentage of CPU usage for the same task can vary wildly.

[knc1]

Hmm...
It might be a useful change for other reasons.

But I agree, better testing is called for to justify changing files in the Amazon image of the filesystem.

Since we can not (yet) de-brick a Kpw, changing files in the Amazon image that might cause an firmware update to fail in way that leaves the Kindle 'bricked' is not a good idea.

Note: There is a patch to U-Boot available from the Freescale Community that will force the SoC to switch to 'Fastboot' mode on the next restart for the MX508 SoC.
A tad bit too invasive of a change to test for my paygrade.

[HarryT]

The CPU isn't being "wasted" when the Kindle is indexing content. It's pegged at 100% because the CPU is working as hard as it can.

[ixtab]

You're getting something seriously wrong here. As NiLuJe said, you're comparing apples with oranges.

Having these "unused" language-specific jar files in the classpath has negligible impact on CPU performance and zero impact on memory requirement.

Why? Because classes are looked up and loaded exactly once in, namely when they are first needed. Say you want to load a ResourceBundle named "squirrel", and your language is ja_JP. Then (at most), the following three classes will be loaded: squirrel_ja_JP, squirrel_ja, squirrel.

While looking up these classes, yes, the "unneeded" jars will be searched. But this is fast, because one only has to look at the jar file's central directory.

So, while I appreciate your effort, I think that this is a really bad idea. You are not gaining anything (except for a speedup that can probably be measured in milliseconds, or at most seconds, over the entire runtime of the Kindle), but you're breaking functionality.

[nasser]

In my PW, there is no directory /usr/java/bin/cvm..

There is only a 1.8MB file called cvm..

Had some fun searching out all *.jar files and filtering them.. see attached zip with list in csv format.. contains only the non english ones..

There are around 200+ language specific jar files.. if we exclude the "en_GB" files, this amounts to around 10MB worth of "wasted" files..

Taking due heed of knc1 and ixtab's warnings, I wouldn't want to remove these files and screw up something..

Still.. some interesting points:

• ad_booklet-xx_YY.jar and AdManager-xx_YY.jar.. my PW is the ad free version.. so why are these files needed..?
• MediaPlayer-xx_YY.jar.. on the soundless PW, what media..? Mebbe this is used for the "silent movie player" kindlet..?
• TopazReader-impl-xx_YY.jar.. what's topaz..? some new format..?
• oobetutorial-xx_YY.jar.. this is the stuff that comes up when you first unbox and start up the kindle..?
• My PW had *en_GB jars.. but no *en_US jars..

[GoSharks]

@nasser-
I can't help with the rest but I'm pretty sure Topaz is an old format (predecessor to mobi).

[ixtab]

Originally Posted by nasser

Still.. some interesting points:
ad_booklet-xx_YY.jar and AdManager-xx_YY.jar.. my PW is the ad free version.. so why are these files needed..?

Because there is a single firmware for all Kindles of the same model. Whether you will be shown ads (or not) is determined by phoning home to Amazon.

MediaPlayer-xx_YY.jar.. on the soundless PW, what media..? Mebbe this is used for the "silent movie player" kindlet..?

No idea, really. But "media" is a very broad term which doesn't only encompass audio and video.

TopazReader-impl-xx_YY.jar.. what's topaz..? some new format..?

Nope, a really old format.

oobetutorial-xx_YY.jar.. this is the stuff that comes up when you first unbox and start up the kindle..?

No idea.

My PW had *en_GB jars.. but no *en_US jars..

en_US is the language that all resource bundles default to and are defined in. Whatever your current locale is, you will fall back to the default locale if no definition for the requested resource is found. And the default, as said before, is en_US. So no need to define it explicitly.

[aditya3098]

MediaPlayer might be the audiobook player

[Sideromelane]

Something I've learned from fifteen years of Windows, and several years of Android - Never, EVER delete system files unless you know EXACTLY what those files are for, and, more importantly, what DEPENDS upon those files. Deleting a jar for something you don't see youself ever using is a good way to soft-brick your kindle four months down the road, once you've forgotten what you deleted, and try opening one specific kindlet or book that depends explicitly upon something you forgot you ever deleted in the first place!

Nothing in the OS takes up so much space that it is essential to get rid of it to cram in more books. Or free up an imaginary % of CPU speed, because that's not how CPU's work.

[twobob]

^-- This.
The space is minimal.

I AM 100% behind any effort to accelerate machine performance.
And I applaud Richies efforts so far.

This one feels risky though.
My two cents.

[richy1989]

Sorry,

I think I made a big mistake.

But I will make any effort to accelerate machine performance still!

Thanks for everyone's help!

[twobob]

not really. IIRC something similar was suggested before.

"Behind you all the way".

Niluje has swapped to a nice new shiny latest toolchain ultimately using the native processing more efficiently; over the course of a project such tiny improvements can of course add up to making a difference so I'm behind you all the way.