Kernel SamePage Merging (KSM)

Azaz memória deduplikáció

• http://ham.to/?p=15
• http://v-kompany.blogspot.hu/2014/07/ksmkernel-samepage-merging.html

echo 1 > /sys/kernel/mm/ksm/run

The effectiveness of KSM and MADV_MERGEABLE is shown in /sys/kernel/mm/ksm/:

pages_shared	how many shared unswappable kernel pages KSM is using
pages_sharing	how many more sites are sharing them i.e. how much saved
pages_unshared	how many pages unique but repeatedly checked for merging
pages_volatile	how many pages changing too fast to be placed in a tree
full_scans	how many times all mergeable areas have been scanned

• A high ratio of pages_sharing to pages_shared indicates good sharing, but a high ratio of pages_unshared to pages_sharing indicates wasted effort.
• pages_volatile embraces several different kinds of activity, but a high proportion there would also indicate poor use of madvise MADV_MERGEABLE.