Thanks for your reply. I understand the complexity of checkpointing a process and I do agree that capturing the complete state of a system is really difficult. So my question is that if a subset of that functinality was to be implemented (e.g. not guaranteeing certain things to processes when they restart, and I believe that you have already implemented this for DragonFly), why is it more difficult to do it for a physical machine versus in a VMM like Xen? Or do you have any arguments in the reverse direction i.e. better/easier/efficient/reliable in a physical machine than a VMM? Or do you now believe since this feature was implemented over a year ago, that a VMM is the way to go?
On Wed, 12 Jan 2005, Kip Macy wrote: > I've promised Nate to port the functionality to FreeBSD. I'm busy doing some > things with the FreeBSD port to Xen at the moment. > > Checkpointing a process is intrinsically messy for reasons beyond the obvious > statefulness of TCP connections. Process state, particularly with regard to > devices, is often not cleanly associated with the process in the kernel. What > happens if a file that the process had open has gone away? Other issues > abound - > checkpointing a process pipeline can be made to work, but some work would need > to be done on pipes. The list goes on. > > > -Kip > > > On Wed, 12 Jan 2005, Siddharth Aggarwal wrote: > > > > > Hi all, > > > > I am responding to a post back in Oct 2003 when the checkpointing feature > > was announced for DragonFly. I have been doing some research on this, and > > have seen some projects that use Xen VMM to achieve checkpoints of guest > > OSes. > > > > So I was looking for inputs from people as to what everyone feels about > > checkpointing, whether it should be done at the physical machine level or > > VM level. Pros and Cons of each approach, if any further development was > > done on DragonFly for checkpoint since then and if it was stopped, why? > > Are there serious limitations to checkpointing a physical machine? > > > > Sorry for such a vague posting, but I thought this would be a good > > platform to get some feedback. > > > > Thanks, > > Sid. > > _______________________________________________ > > freebsd-hackers@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > To unsubscribe, send any mail to "[EMAIL PROTECTED]" > > > > -- > "Debugging is twice as hard as writing the code in the first place. > Therefore, if you write the code as cleverly as possible, you are, > by definition, not smart enough to debug it." - Brian W. Kernighan > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "[EMAIL PROTECTED]" > _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
