init: wait for '/dev/block/bootdevice/by-name/cache' timed out and took 5007ms【学习笔记】

平台信息:
内核：4.9.112
系统：android one
平台：qcom sdm439

作者：庄泽彬(欢迎转载，请注明作者)

一、android设备在开机的时候打印了如下的log，由于系统使用了AB分区，把cache分区和recovery分区干掉了，因此在init.rc文件中等待cache分区的挂载肯定会失败，这样会导致系统开机的时间变慢5秒,因此这部分需要优化，提高系统的开机速度：

1 [   25.411599] init: wait for '/dev/block/bootdevice/by-name/cache' timed out and took 5007ms
2 [   25.411892] init: Command 'wait /dev/block/bootdevice/by-name/cache' action=charger (/system/etc/init/init.xxx.rc:187) took 5007ms and failed: wait_for_file() failed

二、修改方法,找到对应的init.xxx.rc文件:

1 on bootlog
2 #    wait /dev/block/bootdevice/by-name/cache
3     start logcat_boot
4     start kmsg_boot

三、测试对比

 1     未优化之前的时间: 
 2     [   25.206440] Boot completed
 3     [   24.588259] Boot completed
 4     [   24.287756] Boot completed 
 5     [   24.073655] Boot completed
 6     
 7 
 8     优化之后的时间:
 9     [   22.822842] Boot completed
10     [   22.647295] Boot completed
11     [   22.641041] Boot completed
12     [   22.605505] Boot completed