[Ksummit-discuss] [CORE TOPIC] Redesign Memory Management layer and more core subsystem

Christoph Lameter cl at gentwo.org
Fri Jun 13 23:04:52 UTC 2014


On Sat, 14 Jun 2014, Benjamin Herrenschmidt wrote:

> > It is solvable if the objects are inherent movable. If any object
> > allocated provides a function that makes an object movable then
> > defragmentation is possible and therefore large contiguous area of memory
> > can be created at any time.
>
> Another interesting thing is migration of pages with mapped DMA on
> them :-)
>
> Our IOMMUs support that, but there isn't a way to hook that up into
> Linux page migration that wouldn't suck massively at this point.

Well yes that would require a  major rethink. While we are at it we may
as well try to get more done. Maybe we can do that just for a limited
region within the existing memory management. Something like OSV, cgroups
or cpuset that restricts it to certain nodes or cpus where we would allow
this to occur while the rest still runs the standard kernel.

A kind of sidecar approach.


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