Android - Hotplug Off (Multi-Core enable)

If your device has root permission

adb shell stop mpdecision

adb shell "echo 1 > /sys/devices/system/cpu/cpu1/online"

or

# stop mpdecision

# echo 1 > /sys/devices/system/cpu/cpu1/online

# ...

xda - developers

http://forum.xda-developers.com/showthread.php?t=1216197

update 1/31

Support for hot-pluggable CPUs

CONFIG_HOTPLUG_CPU=y

or # CONFIG_HOTPLUG_CPU is not set

http://cateee.net/lkddb/web-lkddb/HOTPLUG_CPU.html

Enable bootchart in the Android

In the Android source code

STEP 1. ----------

In the device side

1. enable bootchart flag

$ export INIT_BOOTCHART=true

2. and build the Android source code

3. After flashing binary

$ adb shell

$ mkdir /data/bootchart

$ echo 60 > /data/bootchart-start

(It means that bootchart log will be saved until 60 seconds)

$ exit

(exit adb)

4. reboot device

$ adb reboot

You can find some log files in the /data/bootchart/ directory

Tip.

- You can find "bootchart.c & bootchart.h" under the ../init/ directory.

- In the same directory there is a Android.mk file.

INIT_BOOTCHART is used in this make file.

STEP 2. ----------

In the linux system side

install bootchart

$ sudo apt-get install bootchart

STEP 3. ----------

after getting bootchart log files

1. copy log files from the Android device to Linux system

$ adb push /data/bootchart/.

2. compress the all log files

$ tar -czf bootchart.tgt *

3. run bootchart

$ bootchart bootchart.tgz

$ ls

bootchart.png bootchart.tgz

* If you meet the error message,

" ZeroDivisionError: flat division by zero"

Please refer to below site: Error while extracting bootchart.tgz and patch the script files.