Messages in this thread | | | Date | Fri, 24 Nov 2006 20:04:49 +0000 (GMT) | From | Mel Gorman <> | Subject | Re: [PATCH 1/11] Add __GFP_MOVABLE flag and update callers |
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On Fri, 24 Nov 2006, Christoph Lameter wrote:
> On Thu, 23 Nov 2006, Linus Torvalds wrote: > >> And the assumption would be that if it's MOVABLE, then it's obviously a >> USER allocation (it it can fail much more eagerly - that's really what the >> whole USER bit ends up meaning internally). > > We can probably make several types of kernel allocations movable if there > would be some benefit from it. >
Page tables are the major type of allocation that comes to mind. From what I've seen, they are the most common long-lived unmovable and unreclaimable allocation.
> Mel already has a problem with mlocked user pages in the movable section. > If this is fixed by using page migration to move the mlocked pages
That is the long-term plan.
> then we > can likely make addititional classes kernel pages also movable and reduce > the amount of memory that is unmovable. If we have more movable pages then > the defrag can work more efficiently.
Indeed, although some sort of placement is still needed to keep these movable allocations together.
> Having most pages movable will also > help to make memory unplug a reality. > > So please do not require movable pages to be user allocations. >
That is not the intention. It just happens that allocations that are directly accessible by userspace are also the ones that are currently movable.
-- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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