how to totally clear the filesytem's cache on linux?
Solution 1:
(it actually drops so..) run sync first, then
free pagecache:
echo 1 > /proc/sys/vm/drop_caches
free dentries and inodes:
echo 2 > /proc/sys/vm/drop_caches
free pagecache, dentries and inodes:
echo 3 > /proc/sys/vm/drop_caches
Then you can start with a clean cache, but of course caching will still work.