How to clear cache in Linux

  • Clear PageCache only
1

sync ; echo 1 > /proc/sys/vm/drop_caches
  • Clear Dentries and inodes(metadata)
1

sync ; echo 2 > /proc/sys/vm/drop_caches
  • Clear All cache(include PageCache and Dentries and inode)
1

sync ; echo 3 > /proc/sys/vm/drop_caches

How to clear swap space in Linux

1

swapoff -a && swapon -a

NOTE: This may make your system unstable when you have low RAM already. The data in the swapspace will force move to your RAM and may cause a OOM when you don’t have free space in RAM.