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On Mon, Jul 22, 2013 at 3:04 PM, Russell Bryant <rbryant at redhat.com> wrote:

> On 07/22/2013 05:15 PM, Alex Glikson wrote:
> > Dear all,
> >
> > Following the initial discussions at the last design summit, we have
> > published the design [2] and the first take on the implementation [3] of
> > the blueprint adding support for multiple active scheduler
> > policies/drivers [1].
> > In a nutshell, the idea is to allow overriding the 'default' scheduler
> > configuration parameters (driver, filters, their configuration
> > parameters, etc) for particular host aggregates. The 'policies' are
> > introduced as sections in nova.conf, and each host aggregate can have a
> > key-value specifying the policy (by name).
> >
> > Comments on design or implementation are welcome!
> >
> > Thanks,
> > Alex
> >
> >
> > [1]
> https://blueprints.launchpad.net/nova/+spec/multiple-scheduler-drivers
> > [2] https://wiki.openstack.org/wiki/Nova/MultipleSchedulerPolicies
> > [3] https://review.openstack.org/#/c/37407/
>
> Thanks for bringing this up.  I do have some comments.
>
> The current design shows 2 different use cases for how a scheduling
> policy would be chosen.
>
> #1 - policy associated with a host aggregate
>
> This seems very odd to me.  Scheduling policy is what chooses hosts, so
> having a subset of hosts specify which policy to use seems backwards.
>
> #2 - via a scheduler hint
>
> It also seems odd to have the user specifying scheduling policy.  This
> seems like something that should be completely hidden from the user.
>
> How about just making the scheduling policy choice as simple as an item
> in the flavor extra specs?
>

++, IMHO we already reveal too much scheduling information to the user via
are current set of scheduler hints.


>
> The design also shows some example configuration.  It shows a global set
> of enabled scheduler filters, and then policy specific tweaks of filter
> config (CPU allocation ratio in the example).  I would expect to be able
> to set a scheduling policy specific list of scheduler filters and
> weights, as well.
>
> --
> Russell Bryant
>
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