Messages in this thread | | | Date | Mon, 4 Dec 2006 14:34:35 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] Add __GFP_MOVABLE for callers to flag allocations that may be migrated |
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On Mon, 4 Dec 2006 20:34:29 +0000 (GMT) Mel Gorman <mel@csn.ul.ie> wrote:
> > IOW: big-picture where-do-we-go-from-here stuff. > > > > Start with lumpy reclaim,
I had lumpy-reclaim in my todo-queue but it seems to have gone away. I think I need a lumpy-reclaim resend, please.
> then I'd like to merge page clustering piece by > piece, ideally with one of the people with e1000 problems testing to see > does it make a difference. > > Assuming they are shown to help, where we'd go from there would be stuff > like; > > 1. Keep non-movable and reapable allocations at the lower PFNs as much as > possible. This is so DIMMS for higher PFNs can be removed (doesn't > exist)
"as much as possible" won't suffice, I suspect. If there's any chance at all that a non-moveable page can land in a hot-unpluggable region then there will be failure scenarios. Easy-to-hit ones, I suspect.
> 2. Use page migration to compact memory rather than depending solely on > reclaim (doesn't exist)
Yup.
> 3. Introduce a mechanism for marking a group of pages as being offlined so > that they are not reallocated (code that does something like this > exists)
yup.
> 4. Resurrect the hotplug-remove code (exists, but probably very stale)
I don't even remember what that looks like.
> 5. Allow allocations for hugepages outside of the pool as long as the > process remains with it's locked_vm limits (patches were posted to > libhugetlbfs last Friday. will post to linux-mm tomorrow).
hm.
I'm not saying that we need to do memory hot-unplug immediately. But the overlaps between this and anti-frag and lumpiness are sufficient that I do think that we need to work out how we'll implement hot-unplug, so we don't screw ourselves up later on.
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