Distributed Process Scheduling Algorithm

Dominik Dingel dingel at linux.vnet.ibm.com
Tue Feb 16 03:42:52 EST 2016

On Tue, 16 Feb 2016 00:13:34 -0500
Valdis.Kletnieks at vt.edu wrote:

> On Tue, 16 Feb 2016 10:18:26 +0530, Nitin Varyani said:
> > 1) Sending process context via network
> Note that this is a non-trivial issue by itself.  At a *minimum*,
> you'll need all the checkpoint-restart code.  Plus, if the process
> has any open TCP connections, *those* have to be migrated without
> causing a security problem.  Good luck on figuring out how to properly
> route packets in this case - consider 4 nodes through,
> you migrate a process from to,  How do you make sure
> *that process*'s packets go to 0.3 while all other packets still go to
> 0.1.  Also, consider the impact this may have on iptables, if there is
> a state=RELATED,CONNECTED on 0.1 - that info needs to be relayed to 0.3
> as well.
> For bonus points, what's the most efficient way to transfer a large
> process image (say 500M, or even a bloated Firefox at 3.5G), without
> causing timeouts while copying the image?
> I hope your research project is *really* well funded - you're going
> to need a *lot* of people (Hint - find out how many people work on
> VMWare - that should give you a rough idea)

I wouldn't see things that dark. Also this is an interesting puzzle.

To migrate processes I would pick an already existing solution.
Like there is for container. So every process should be, if possible, in a container.
To migrate them efficiently without having some distributed shared memory,
you might want to look at userfaultfd.

So now back to the scheduling, I do not think that every node should keep track
of every process on every other node, as this would mean a massive need for
communication and hurt scalability. So either you would implement something like work stealing or go for a central entity like mesos. Which could do process/job/container scheduling for you.

There are now two pitfalls which are hard enough on their own:
- interprocess communication between two process with something different than a socket
  in such an case you would probably need to merge the two distinct containers

- dedicated hardware


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