Minimum Overhead Memory Snapshots – Latency-reduced Copy-on-Write Mechanism in Userspace

  • Type: Master thesis
  • State: open
  • Supervisor: Ralf Ramsauer
  • Student: No Name

Copy-on-Write memory snapshots in userspace can be achieved by various methods: fork(), userfaultfd, mmap(), ... Some of those methods duplicate page tables, and mark the origin as R/O. Subsequent changes (i.e., writes) to the origin will cause exception handlers to eventually "copy-on-write".

In case of numerous page table entries, copying the page tables can consume a significant amount of time, which blocks the calling task. In this work, a methodology shall be developed that is able to "hide" that latency in order to reduce the amount of time that is required to finalise a memory snapshot.