On Wed, 2019-01-23 at 10:48 +0200, Amir Goldstein wrote: > Hi, > > In his session about "reflink" in LSF/MM 2016 [1], Darrick Wong > brought up the subject of sharing pages between cloned files and the > general vibe in room was that it could be done. This subject has been around for a while. We talked about cache sharing for containers in LSF/MM 2013, although it was as a discussion within a session rather than a session about it. At that time, Parallels already had an out of tree implementation of a daemon that forced this sharing and docker was complaining about the dual caching problem of their graph drivers. So, what we need in addition to reflink for container images is something like ksm for containers which can force read only sharing of pages that have the same content even though they're apparently from different files. This is because most cloud container systems run multiple copies of the same container image even if the overlays don't necessarily reflect the origin. Essentially it's the same reason why reflink doesn't solve the sharing problem entirely for VMs. James
