Hey, sorry for necroposting. I completely missed this thread when it was active, but Russel just pointed it out to me on Twitter earlier today and I couldn't help myself.
2013/7/19 Sandy Walsh <sandy.wa...@rackspace.com>: > On 07/19/2013 05:01 PM, Boris Pavlovic wrote: > Sorry, I was commenting on Soren's suggestion from way back (essentially > listening on a separate exchange for each unique flavor ... so no > scheduler was needed at all). It was a great idea, but fell apart rather > quickly. I don't recall we ever really had the discussion, but it's been a while :) Yes, when moving beyond simple flavours, the idea as initially proposed falls apart. I see two ways to fix that: * Don't move beyond simple flavours. Seriously. Amazon have been pretty darn succesful with just their simple instance types. * If you must make things complicated, use fanout to send a reservation request: - Send out reservation requests to everyone listening (*) - Compute nodes able to accommodate the request reserve the resources in question and respond directly to the requestor. Those unable to accommodate the request do nothing. - Requestor (scheduler, API server, whatever) picks a winner amongst the repondants and broadcasts a message announcing the winner of the request. - The winning node acknowledges acceptance of the task to the requestor and gets to work. - Every other node that responded also sees the broadcast and cancels the reservation. - Reservations time out after 5 seconds, so a lost broadcast doesn't result in reserved-but-never-used resources. - If noone has volunteered to accept the reservation request within a couple of seconds, broadcast wider. (*) "Everyone listening" isn't necessarily every node. Maybe you have topics for nodes that are at less than 10% utilisation, one for less than 25% utilisation, etc. First broadcast to those at 10% or less, move on to 20%, etc. This is just off the top of my head. I'm sure it can be improved upon. A lot. My point is just that there's plenty of alternatives to the omniscient schedulers that we've been used to for 3 years now. -- Soren Hansen | http://linux2go.dk/ Ubuntu Developer | http://www.ubuntu.com/ OpenStack Developer | http://www.openstack.org/ _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev