[MOD JB, ICS, GB / 31/01] CrossBreeder (uRandom) for entropy based lag reduction

naudmick said:

Hi,

This is a combination of 3 different methodologies to reduce Android lag due to low entropy.

1. Change wakeup threshold kernel parameters ala KAK.
2. Run rngd ala Seeder but not in intensive feed mode.
3. Remove /dev/random as it's blocking. Link it to non-blocking /dev/urandom. Since /dev/random is blocking and designed to protect us from Quantum alien cryptographers with mathematical certainty and urandom is non blocking pseudo-random device that most apps and OSs are using anyway.

I'm getting some good results on all Android devices I've tried this on.

You can check your results with this tool:

http://play.google.com/store/apps/de...ndentropyavail

You should get consistent values around the maximum 4096 with this mod.

This is the listing of /etc/init.d/00CrossBreeder (Can be run manually too) :

Code:

#!/system/bin/sh
busybox sysctl -w kernel.random.write_wakeup_threshold=4096
busybox sysctl -w kernel.random.read_wakeup_threshold=1333
rm /dev/random && ln /dev/urandom /dev/random
busybox mknod -m 666 /dev/random.fake c 1 8
busybox chown root.root /dev/random.fake
rngd -t 30 -T 1 -s 256 -W 80% -o /dev/random.fake
sleep 2
echo -8 > /proc/$(busybox pgrep rngd)/oom_adj
renice 5 `busybox pidof rngd`
rm /dev/random.fake

Your thoughts and experiences welcome.

Notes:

1. You can put the code in /etc/init.d/00CrossBreeder and make it executable with:

chmod 755 /etc/init.d/00CrossBreeder

This should run on every boot if you have init.d support. You can also run it manually.

2. You'll need to rename the attached rngd.img binary to /system/xbin/rngd and make it executable with:

cp rngd.img /system/xbin/rngd
chmod 755 /system/xbin/rngd

3. You'll need to stop the seeder service and disable auto start ( IMPORTANT as seeder rngd can take high cpu with the link enabled). Though you can run the app to see available entropy.

or flash zip ( update 29/01/13 ) => CrossBreederByMick.zip

CREDITS:

1. Seeder. This rngd binary is from the seeder util. ( http://xdaforums.com/show...php?p=33999592 )
2. KAK ( http://xdaforums.com/show...php?p=12058585 ).

Click to expand...

Click to collapse

DuTY09 said:

had this running on flinnys cm10.1 since the morning and so far so good

Click to expand...

Click to collapse

remusator said:

Can you translate it to "human language" ?
Or is it for devs only ?

Click to expand...

Click to collapse

leimrey said:

So all we need is to flash the crossbreed zip? What about the rngd.img? fastboot flash?
Sorry but, i can't understand @_@

Click to expand...

Click to collapse

I should've learned by now that sarcasm doesn't translate well on the internet

So to be clear... IMNSHO, the recent entropy pool fad is bull****. The only users of /dev/random are libcrypto (used for cryptographic operations like SSL connections, ssh key generation, and so on), wpa_supplicant/hostapd (to generate WEP/WPA keys while in AP mode), and the libraries that generate random partition IDs when you do an ext2/3/4 format. None of those 3 users are in the path of app execution, so feeding random from urandom does nothing except make random... well... less random

The only conceivable reason some devices may feel faster is because by constantly polling the PRNG, it keeps the device's I/O in constant use (which in turn, depending on device, will make the CPU stick to higher clock frequencies to keep up and/or ramp up the IO scheduler).

Click to expand...

Click to collapse

dan-fish said:

Just for anyone who hasn't seen it. This was posted by arcee on his G+
https://plus.google.com/115049428938715274412/posts/GWr72W9zmY2



I'm not hating on the OP or anything, just thought I'd share the info.

Click to expand...

Click to collapse