[openstack-dev] Scheduler proposal

Chris Friesen chris.friesen at windriver.com
Sat Oct 10 00:33:38 UTC 2015

On 10/09/2015 03:36 PM, Ian Wells wrote:
> On 9 October 2015 at 12:50, Chris Friesen <chris.friesen at windriver.com
> <mailto:chris.friesen at windriver.com>> wrote:
>     Has anybody looked at why 1 instance is too slow and what it would take to
>         make 1 scheduler instance work fast enough? This does not preclude the
>         use of
>         concurrency for finer grain tasks in the background.
>     Currently we pull data on all (!) of the compute nodes out of the database
>     via a series of RPC calls, then evaluate the various filters in python code.
> I'll say again: the database seems to me to be the problem here.  Not to
> mention, you've just explained that they are in practice holding all the data in
> memory in order to do the work so the benefit we're getting here is really a
> N-to-1-to-M pattern with a DB in the middle (the store-to-DB is rather
> secondary, in fact), and that without incremental updates to the receivers.

I don't see any reason why you couldn't have an in-memory scheduler.

Currently the database serves as the persistant storage for the resource usage, 
so if we take it out of the picture I imagine you'd want to have some way of 
querying the compute nodes for their current state when the scheduler first 
starts up.

I think the current code uses the fact that objects are remotable via the 
conductor, so changing that to do explicit posts to a known scheduler topic 
would take some work.


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