KSM is a linux driver that allows dynamically sharing identical memory
pages between one or more processes. Unlike traditional page sharing
that is made at the allocation of the memory, ksm do it dynamically
after the memory was created. Memory is periodically scanned;
identical pages are identified and merged. The sharing is unnoticeable
by the process that use this memory. (the shared pages are marked as
readonly, and in case of write do_wp_page() take care to create new
copy of the page).