Minimum set of primitives?

Chris Bitmead
Fri, 20 Mar 1998 07:16:00 +0000

Kragen wrote:
> On Fri, 20 Mar 1998, Chris Bitmead wrote:
> > Yes, I can't see how you can get away from the need for a
> > "commit" function, which says to the system that the current
> > state is a place that can be recovered from if things crash. Of
> > course not all applications will care to use it, but some will
> > definitely need it, maybe even most.
> KeyKOS got away from it for most applications by simply checkpointing
> the entire system periodically -- every couple of minutes.  Wrote the
> full contents of memory, the complete states of all processes,
> everything.  Then, if the system crashed, it's as if everything between
> the last full checkpoint and the reboot never happened -- it's as
> though the system never stopped running, from the applications' point
> of view.

I can't see how you can do that with even half reasonable
efficiency without special hardware - i.e. involatile memory.

Unless you want to stop the whole system from time to time to
checkpoint everything, but don't people hate emacs when it stops
to garbage collect? I can't see this as feasible. What you talk
about would be great, but I can't see it being realistic.

Chris Bitmead