如何提高SD Card的读取及写入速度？
Many of us are disappointed about the reading speed of the SD Cards on our Android Phones. It doesn‘t matter if you have fast 10 Class SD Card， it performs very poorly on the Phone comparing how it performs on the PC.（我们许多人对自己手机SD卡的读取速度失望，当然如果你有 Class 10（是指型号等级）的卡那就无所谓，不过在手机上的表现也不如在电脑上）
The clue is the Cache size for reading from SD Card. It’s set to 128 KB， on some ROM‘s even to 4 KB！（原因在于手机中 Cache 的值的大小，有的手机是128KB，有的甚至更小）
You can check for yourself your Cache size by looking into this file：（你可以在手机上的以下路径查看自己手机的Cache值）
/sys/devices/virtual/bdi/179:0/read_ahead_kb
You can change it manually but it will be reverted to default on the reboot. The changes need to be done permanently by loading the script on the startup through the init.d.
（你可以手动改变这个值，但是重启之后又会回到默认的值。原因是启动时会加载init.d这个文件）
Or you can flash the CWM zip files that I made for you.（或者你可以刷我提供的这个CWM zip 包来解决）
You must find which Cache size fits best for your SD Card. In my case its the 3072 KB Cache size.At best， use the Root Explorer to change the value， then run SD Tools Benchmark - finally flash the CWM zip file that fits your SD Card.（你要自己找到适合自己手机的值，我的3072最好。可以用RE管理器来改变这个值，然后用SD工具软件来测试这个值对应的读取情况，最后觉得来刷哪个包）
The Benchmark is made with the SD Tools program. Caution： The SD Tools developer states that his benchmark sometimes gives inaccurate readings.
If you want to convince yourself of the speed improvement after applying the fix， just open your Gallery and see how fast it loads the photos！（你可以根据打开图库图片的快慢来查看是否生效）
Suggestion：2048 KB Cache size performs at best for most of the SD Cards！（大部分的手机内存卡用2048这个值最好）
