Messages in this thread | | | Subject | Re: [ckrm-tech] [PATCH] BC: resource beancounters (v4) (added user memory) | From | Chandra Seetharaman <> | Date | Thu, 14 Sep 2006 16:42:44 -0700 |
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On Thu, 2006-09-14 at 11:53 +0400, Pavel Emelianov wrote:
<snip>
> > What if I have 40 containers each with 2% guarantee ? what do we do > > then ? and many other different combinations (what I gave was not the > > _only_ scenario). > > > Then you need to solve a set of 40 equations. This sounds weird, but > don't afraid - sets like these are solved lightly.
extrapolate that to a varying # of permutations and real time changes in the system workload. Won't it be complex ?
Wouldn't it be a lot simpler if we have the guarantee support instead ? Why you do not like guarantee ? :)
<snip>
> >> Then how do you make sure that memory WILL be available when the group needs > >> it without limiting the others in a proper way? > >> > > > > You could limit others only if you _know_ somebody is not getting what > > they are supposed to get (based on guarantee). > > > I don't understand your idea. Limit does _not_ imply anything - it's > just a limit.
I didn't mean "limit" as defined in BC. I meant it in the generic sense. IOW, if we have to provide guarantees then it would limit other RGs from getting that (amount of guaranteed) resource.
> You may limit anything to anyone w/o bothering the consequences. > Guarantee implies that the resource you guarantee will be available and > this "will be" is something not that easy. > > So I repeat my question - how can you be sure that these X megabytes you > guarantee to some group won't be used by others so that you won't be able > to reclaim them?
It depends on how the memory controller is implemented. It could be implemented in different ways: - reclamation path will _not_ free pages belonging to a RG that is below its guarantee. - allocation from a "over guarantee" RG can succeed iff there is memory after satisfying all guarantees (or will free pages from the requesting RG before it will succeed). - ...
BTW, my point is to have guarantees for _all_ resources not just memory.
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---------------------------------------------------------------------- Chandra Seetharaman | Be careful what you choose.... - sekharan@us.ibm.com | .......you may get it. ----------------------------------------------------------------------
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