Difference between revisions of "CR tools"
| Line 14: | Line 14: | ||
The checkpoint procedure relies heavily on '''/proc''' file system (it's a general place where crtools takes all the information it needs). | The checkpoint procedure relies heavily on '''/proc''' file system (it's a general place where crtools takes all the information it needs). | ||
| + | Which includes: | ||
| − | |||
* Files descriptors information (via '''/proc/$pid/fd''' and '''/proc/$pid/fdinfo''') | * Files descriptors information (via '''/proc/$pid/fd''' and '''/proc/$pid/fdinfo''') | ||
* Pipes parameters | * Pipes parameters | ||
* Memory maps (via '''/proc/$pid/maps''') | * Memory maps (via '''/proc/$pid/maps''') | ||
| − | + | The process dumper (lets call it simply the dumper further) does the following steps during checkpoint stage: | |
| + | |||
| + | # A '''$pid''' of a process group leader is obtained from the command line | ||
| + | # By using this '''$pid''' the dumper walks though '''/proc/$pid/status''' and gathers children '''$pids''' recursively. At the end we will have a process tree. | ||
| + | # Then it takes every '''$pid''' from a process tree, sends ''SIGSTOP'' to every process found, and performs the following steps on each '''$pid''' | ||
| + | #* Collects VMA areas by parsing '''/proc/$pid/maps''' | ||
| + | #* | ||
Revision as of 21:17, 14 October 2011
What CRtools is
CRtools is an utility to checkpoint/restore process tree. Unlike checkpoint/restore implemented completely in kernel space, it tries to achieve the same target mostly in user space.
Agenda
- Basic design (checkpoint == proc + SEIZE, restore == syscalls + execve)
- What's required from kernel
Basic design
Checkpoint
The checkpoint procedure relies heavily on /proc file system (it's a general place where crtools takes all the information it needs). Which includes:
- Files descriptors information (via /proc/$pid/fd and /proc/$pid/fdinfo)
- Pipes parameters
- Memory maps (via /proc/$pid/maps)
The process dumper (lets call it simply the dumper further) does the following steps during checkpoint stage:
- A $pid of a process group leader is obtained from the command line
- By using this $pid the dumper walks though /proc/$pid/status and gathers children $pids recursively. At the end we will have a process tree.
- Then it takes every $pid from a process tree, sends SIGSTOP to every process found, and performs the following steps on each $pid
- Collects VMA areas by parsing /proc/$pid/maps
