android-tune2fs

Nexus7(2012)が遅い。

ext4 のジャーナルは HDD アクセス速度を大幅に低下させるらしい。

$ ls -l /dev/block/platform/sdhci-tegra.3/by-name/
$ mount -o remount,rw /
$ vi /fstab
# noatime
or 
# TWRP
$ tune2fs -O ^has_journal /dev/block/mmcblk0p11
$ tune2fs -O ^has_journal /dev/block/mmcblk0p12
$ tune2fs -O ^has_journal /dev/block/mmcblk0p13

ref :

https://qtotter.wordpress.com/2016/11/21/amazon-fire-5th-gen%E3%81%8C%E7%88%86%E9%80%9F%E3%81%AB%E3%81%AA%E3%81%A3%E3%81%9F/

http://redtiger.tank.jp/wiki/doku.php?id=linux-handling-note:disable-ext4-journal

https://forum.xda-developers.com/showthread.php?t=1739119

APP -> system
CAC -> cache
LNX -> boot.img
MDA -> Unknown
MSC -> Misc (bootloader commands and other misc stuff )
PER -> usually a fat partition containing sensor calibration etc. - per device provisioned.
SOS -> recovery.img
UDA -> /data - "user data area"
USP -> Staging