I've seen sysadmins playing with /proc/sys/vm/drop_caches (echo 3 into this file from a cron) in order to free caches. Is there a real interrest in doing this? Aren't the clean caches reclaimed when needed?
Thanks.
In normal operation it's not necessary. The normal reason for doing it is to be able to test the performance of some program when it is running with a cold cache.