Re: [ckrm-tech] [PATCH 4/7] UBC: syscalls (user interface)

Magnus Damm
2006-08-22T03:57:54Z

On Mon, 2006-08-21 at 18:16 -0700, Rohit Seth wrote:
> On Mon, 2006-08-21 at 11:47 +0900, Magnus Damm wrote:
> > On Fri, 2006-08-18 at 07:45 -0700, Dave Hansen wrote:
> > > On Fri, 2006-08-18 at 12:08 +0400, Andrey Savochkin wrote:
> > > >
> > > > A) Have separate memory management for each container,
> > > > with separate buddy allocator, lru lists, page replacement mechanism.
> > > > That implies a considerable overhead, and the main challenge there
> > > > is sharing of pages between these separate memory managers.
> > >
> > > Hold on here for just a sec...
> > >
> > > It is quite possible to do memory management aimed at one container
> > > while that container's memory still participates in the main VM.
> > >
> > > There is overhead here, as the LRU scanning mechanisms get less
> > > efficient, but I'd rather pay a penalty at LRU scanning time than divide
> > > up the VM, or coarsely start failing allocations.
> >
> > This could of course be solved with one LRU per container, which is how
> > the CKRM memory controller implemented things about a year ago.
>
> Effectively Andrew's idea of faking up nodes is also giving per
> container LRUs.

Yes, but the NUMA emulation approach is using fixed size containers
where the size is selectable at the kernel command line, while the CKRM
(and pzone) approach provides a more dynamic (and complex) solution.

/ magnus