linux下清空磁盘缓存

测试程序性能的时候，之前的时候需要不停的重启机器来进行测试，比较麻烦，想有什么办法可以清空磁盘缓存呢？

If you're on OS X, the 'purge' command (part of the CHUD developer tools) will cause the disk caches to be purged. On Linux, with a 2.6.16 kernel or newer, 'echo 3 > /proc/sys/vm/drop_caches' will achieve the same effect. Another trick on Linux is to use a separate filesystem for the benchmark--if you perform a umount/mount cycle
after each run the kernel will drop any cached data that came from that filesystem.

两种方法：
echo 3 > /proc/sys/vm/drop_caches
umount /dev/sdx

参考：
http://www.gamedev.net/community/forums/topic.asp?topic_id=402069
http://blog.chinaunix.net/u/27173/showart_467689.html