On Thu, 2009-11-26 at 17:10 +0100, Christian Ehrhardt wrote:Some sort of, its on s390 which does that all the time. By default there is a daemon that activates/deactivates cpus according to load to cover load peaks but also save virtualization overhead.
What I consider more important at the moment is that there is no hook to recalculate these values in case cpu hot add/remove takes place.
As an example someone could boot a machine with one online cpu and get the low non scaled defaults, later on driven by load the system activates more and more processors. Therefore the system could end up having a large amount of cpus with non recalculated scheduler tunables.
This is virt junk that's playing dumb games with hotplug isn't it?
Normal machines simply don't change their numbers of cpus, if theyWhat is still "normal" today, you cant get s390 without virt so I would consider it normal and a real use case for us :-)
hotplug its usually for things like suspend or actual replacement of a
faulty piece of kit, in which case there's little point in adjusting
things.
Aside from that, we probably should put an upper limit in place, as II agree to that, but in the code is already an upper limit of 200.000.000 - well we might discuss if that is too low/high.
guess large cpu count machines get silly large values