CR tools
What CRtools is
CRtools is an utility to checkpoint/restore process tree. Unlike checkpoint/restore implemented completely in kernel space, it tries to achieve the same target mostly in user space.
Agenda
- Basic design (checkpoint == proc + SEIZE, restore == syscalls + execve)
- What's required from kernel
Basic design
Checkpoint
The checkpoint procedure relies heavily on /proc file system (it's a general place where crtools takes all the information it needs).
This includes:
- Files descriptors information (via /proc/$pid/fd and /proc/$pid/fdinfo)
- Pipes parameters
- Memory maps (via /proc/$pid/maps)
Though not all parameters can be observed this way, say the current brk() value of a process is not exported at all.
