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| − | + | == What CRtools is == | |
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| + | '''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. | ||
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| + | === Agenda === | ||
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| + | # Basic design (checkpoint == proc + SEIZE, restore == syscalls + execve) | ||
| + | # What's required from kernel | ||
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| + | == Basic design == | ||
| + | |||
| + | === Checkpoint === | ||
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| + | The checkpoint procedure relies heavily on '''/proc''' file system (it's a general place where crtools takes all the information it needs). | ||
| + | Which includes: | ||
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| + | * Files descriptors information (via '''/proc/$pid/fd''' and '''/proc/$pid/fdinfo''') | ||
| + | * Pipes parameters | ||
| + | * Memory maps (via '''/proc/$pid/maps''') | ||
| + | |||
| + | The process dumper (lets call it simply the dumper further) does the following steps during checkpoint stage: | ||
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| + | # A '''$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''' | ||
| + | #* | ||
