Re: [ckrm-tech] [PATCH] BC: resource beancounters (v4) (added user memory)

[Balbir Singh <balbir@in.ibm.com>]

Pavel Emelianov wrote:
> Balbir Singh wrote:
> > Dave Hansen wrote:
> > > On Fri, 2006-09-08 at 11:33 +0400, Pavel Emelianov wrote:
> > > > I'm afraid we have different understandings of what a "guarantee" is.
> > > It appears so.
> > >
> > > > Don't we?
> > > > Guarantee may be one of
> > > >
> > > >   1. container will be able to touch that number of pages
> > > >   2. container will be able to sys_mmap() that number of pages
> > > >   3. container will not be killed unless it touches that number of
> > > > pages
> > > A "death sentence" guarantee?  I like it. :)
> > >
> > > >   4. anything else
> > > >
> > > > Let's decide what kind of a guarantee we want.
> > I think of guarantees w.r.t resources as the lower limit on the resource.
> > Guarantees and limits can be thought of as the range (guarantee, limit]
> > for the usage of the resource.
> >
> > > I think of it as: "I will be allowed to use this many total pages, and
> > > they are guaranteed not to fail."  (1), I think.  The sum of all of the
> > > system's guarantees must be less than or equal to the amount of free
> > > memory on the machine. 
> > Yes, totally agree.
>
> Such a guarantee is really a limit and this limit is even harder than
> BC's one :)
>
> E.g. I have a node with 1Gb of ram and 10 containers with 100Mb
> guarantee each.
> I want to start one more. What shall I do not to break guarantees?

Don't start the new container or change the guarantees of the existing ones
to accommodate this one :) The QoS design (done by the administrator) should
take care of such use-cases. It would be perfectly ok to have a container
that does not care about guarantees to set their guarantee to 0 and set
their limit to the desired value. As Chandra has been stating we need two
parameters (guarantee, limit), either can be optional, but not both.


> > > If we knew to which NUMA node the memory was going to go, we might as
> > > well take the pages out of the allocator.
> > >
> > > -- Dave


--

	Balbir Singh,
	Linux Technology Center,
	IBM Software Labs
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/