[Bizgres-general] Statement Queuing take II - Resource Scheduling

[Jim C. Nasby]

On Thu, Jun 29, 2006 at 05:34:26PM +1200, Mark Kirkwood wrote:
> Josh Berkus wrote:
> >
> >
> >> One question is what about roles assigned to other roles? Do you always
> >> use the limits of the lowest role in the tree, or are limits cumulative?
> >
> > Lowest role in the tree.   Otherwise, it's a foot-gun.
> >
> >
> 
> I'm coming back to this, as I've gotten myself confused after thinking 
> about it some more :-).
> 
> I wondering about the definition of 'lowest role in the tree':
> 
>  If it is 'the role with the lowest resource limits', then this is 
> potentially not defined when there is more than one resource limit type 
> - e.g. (inventing some extra limit types as we go) suppose  role 'A' has 
> cpu limit 90 and memory limit 80  and role 'B' has  them the other way 
> around, if I am a member of 'A' and 'B' it is not possible to decide 
> which role to use with this definition.
 
You could take the minimum of all limits...

> If it means the 'the role closest to us in the membership list', then 
> this can also suffer from 2 roles being equally 'close'.
> 
> I'm wondering if there needs to be a check along the lines of 'you can 
> only be a member of 1 group with resource limits enabled'?
> 
> Any thoughts (of have I just missed something obvious)?

I'm thinking that for the first pass maybe we should only look at
whatever role you have active at the time. Or, take the minimum of all
limits that apply to roles that are directly INHERITed by the current
role, if SET ROLE hasn't been used. Once we have a better idea of how
people are using resource limits, I think it'll be a lot easier to
decide what to do when there's a whole tree of limits to deal with.

Though, if this is the route we take, we should make it very clear in
the docs that things will change in a future version.
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby at pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461