On Sun, 2011-05-29 at 13:46 +0530, Ankita Garg wrote:

quoted

It's worth noting that we already do targeted reclaim on boundaries
other than zones.  The lumpy reclaim and memory compaction logically do
the same thing.  So, it's at least possible to do this without having
the global LRU designed around the way you want to reclaim.

My understanding maybe incorrect, but doesn't both lumpy reclaim and
memory compaction still work under zone boundary ? While trying to free
up higher order pages, lumpy reclaim checks to ensure that pages that
are selected do not cross zone boundary. Further, compaction walks
through the pages in a zone and tries to re-arrange them.

I'm asserting that we don't need memory regions in the

	pgdat->regions[]->zones[]

layout to do what you're asking for.

Lumpy reclaim is limited to a zone because it's trying to satisfy and
allocation request that came in for *THAT* *ZONE*.  It's useless to go
clear out other zones.  In your case, you don't care about zone
boundaries: you want to reclaim things regardless.

There was a "cma: Contiguous Memory Allocator added" patch posted a bit
ago to linux-mm at .  You might want to take a look at it for some
inspiration.

I think you also need to clearly establish here why any memory that
you're going to want to power off can't use (or shouldn't use)
ZONE_MOVABLE.  It seems a bit silly to have it there, and ignore it for
such a similar use case.  Memory hot-remove and power-down are not
horrifically different beasts.

BTW, that's probably something else to add to your list: make sure
mem_map[]s for memory in a region get allocated *in* that region. 

-- Dave