Re: Back to the future.

Daniel Pittman
2007-04-27T10:55:34Z

Olivier Galibert <galibert@pobox.com> writes:
> On Fri, Apr 27, 2007 at 06:50:56AM +1000, Nigel Cunningham wrote:
>
>> I'm perfectly willing to think through some alternate approach if you
>> suggest something or prod my thinking in a new direction, but I'm
>> afraid I just can't see right now how we can achieve what you're
>> after.
>
> Ok, what about this approach I've been mulling about for a while:
>
> Suspend-to-disk is pretty much an exercise in state saving. There are
> multiple ways to do state saving, but they tend to end up in two
> categories: implicit and explicit.

[...]

> In explicit state saving each object saves what is needed from its
> state to an independently defined format (instead of "whatever the
> memory organization happens to be at that point"). When reloading the
> state you have to parse it, and it usually requires
> rebuilding/relocating all references/pointers/etc.

If you are looking seriously at this you might want to start with the
code in the OpenVZ kernel (http://openvz.org) that allows a VE to
"checkpoint" to disk and "restore" on the same or a different machine.

This is, as far as I can tell, a portable implementation of this that
already handles real live userspace applications moving transparently
between two machines.

It has the advantage that it lives in an orderly world where most
devices and the file system are virtual but, hey, it works right now.

Regards,
Daniel
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