Messages in this thread | | | Date | Wed, 30 Sep 2009 21:00:53 +0530 | From | Balbir Singh <> | Subject | Re: [RFC v2 PATCH 0/8] CFS Hard limits - v2 |
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* Pavel Emelyanov <xemul@openvz.org> [2009-09-30 19:10:27]:
> Balbir Singh wrote: > > * Pavel Emelyanov <xemul@openvz.org> [2009-09-30 17:36:29]: > > > >> Bharata B Rao wrote: > >>> Hi, > >>> > >>> Here is the v2 post of hard limits feature for CFS group scheduler. This > >>> RFC post mainly adds runtime borrowing feature and has a new locking scheme > >>> to protect CFS runtime related fields. > >>> > >>> It would be nice to have some comments on this set! > >> I have a question I'd like to ask before diving into the code. > >> Consider I'm a user, that has a 4CPUs box 2GHz each and I'd like > >> to create a container with 2CPUs 1GHz each. Can I achieve this > >> after your patches? > > > > I don't think the GHz makes any sense, consider CPUs with frequency > > scaling. If I can scale from 1.6GHz to say 2.6GHz or 2GHz to 4GHz, > > what does it mean for hard limit control? Hard limits define control > > over existing bandwidth, anything else would be superficial and hard > > hard to get right for both developers and users. > > Two numbers for configuring limits make even less sense OTOH ;) > By assigning 2GHz for 4GHz CPU I obviously want half of its power ;) > Please, see my reply to vatsa@ in this thread.
But it makes life more difficult for the administrator to think in terms of GHz -- no? Specifically with different heterogeneous systems. I think it would be chaotic in a data center to configure GHz for every partition. Not to say that it makes it even more confusing when running on top of KVM. Lets say I create two vCPUs and I specifiy GHz outside, do I expect to see it in /proc/cpuinfo?
I'd like to hear what others think about GHz as well.
-- Balbir
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