How to Clear Cache in Linux?
Every Linux System has three options to clear cache without interrupting any processes or services.
1. Clear PageCache only.
# sync; echo 1 > /proc/sys/vm/drop_caches
2. Clear dentries and inodes.
# sync; echo 2 > /proc/sys/vm/drop_caches
3. Clear pagecache, dentries, and inodes.
# sync; echo 3 > /proc/sys/vm/drop_caches
test before / after memory
# free -h