Checkpoint/restart (was Re: [PATCH 0/4] - v2 - Object creation with a specified id)
Eric W. Biederman
ebiederm at xmission.com
Thu Jul 10 11:55:34 PDT 2008
"Serge E. Hallyn" <serue at us.ibm.com> writes:
>> So, the checkpoint-as-a-corefile idea sounds good to me, but it
>> definitely leaves a lot of questions about exactly how we'll need to do
>> the restore.
> Talking with Dave over irc, I kind of liked the idea of creating a new
> fs/binfmt_cr.c that executes a checkpoint-as-a-coredump file.
> One thing I do not like about the checkpoint-as-coredump is that it begs
> us to dump all memory out into the file. Our plan/hope was to save
> ourselves from writing out most memory by:
> 1. associating a separate swapfile with each container
> 2. doing a swapfile snapshot at each checkpoint
> 3. dumping the pte entries (/proc/self/)
> If we do checkpoint-as-a-coredump, then we need userspace to coordinate
> a kernel-generated coredump with a user-generated (?) swapfile snapshot.
> But I guess we figure that out later.
Well it is a matter of which VMAs you dump. For things that are file backed
you need to dump them.
I don't know that even a binfmt for per process level checkpoints is sufficient
but I do know having something of that granularity looks much easier. Otherwise
it takes a bazillian little syscalls to do things no one else is interested in doing.
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