Re: -mm merge plans -- anti-fragmentation

[KAMEZAWA Hiroyuki]

On Tue, 10 Jul 2007 12:12:02 +0100
mel@xxxxxxxxx (Mel Gorman) wrote:
> > For (2), we need some method for specifing the range we will remove. For doing that,
> > ZONE seems to be good candidate.  Now we use "kernelcore=" boot option to create
> > ZONE_MOVABLE by hand.
> 
> At the risk of putting you on the spot, do you mind saying whether the
> grouping pages by mobility and ZONE_MOVABLE patches are going in the
> direction you want or should something totally different be done? If
> they are going the right direction, is there anything critical that is
> missing right now?
> 
"grouping pages by mobility and ZONE_MOVABLE" things are what I want. And
I want to go with them. But I know some people doesn't want to increase #
of zones. It is my concern. 
I know ZONE_MOVABLE works well but there are people who don't want new zone.
So making ZONE_MOVABLE as configurable will be good thing, as Nick Piggin pointed.

About my other concerns , see node hotplug (below).

> > But this is the first step. I know Intel guy posted
> > his idea to specify Hotpluggable-Memory range in SRAT (by firmware).
> 
> There may be additional work required to make this play nicely with
> ZONE_MOVABLE but it shouldn't be anything fundamental.
> 
yes. And I don't know his idea about SRAT is acceped in firmware comunity or not.
For now, kernelcore= works enough for memory hotplug.

> > And I think that
> > other method may be introduced for node-hotplug. 
> > 
> 
> Same as above really. If the node contains one zone - ZONE_MOVABLE, it
> would work for unplugging.
> 
Our concern on node hotplug is "bootmem" and hashtable , pgdata, memmap etc....
NUMA initilization (of each arch) includes something complicated.
But this is not directly related to ZONE_MOVABLE things I think.
It's node-hotplug problem.
We are now consdiering hot-add nodes after initcalls().

-Kame

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