Messages in this thread |  | | Date | Fri, 8 Sep 2006 10:24:59 +0100 (IST) | From | Mel Gorman <> | Subject | Re: [PATCH 0/8] Avoiding fragmentation with subzone groupings v25 |
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On Fri, 8 Sep 2006, Peter Zijlstra wrote:
> On Thu, 2006-09-07 at 17:58 -0700, Andrew Morton wrote: >> On Thu, 7 Sep 2006 20:03:42 +0100 (IST) >> Mel Gorman <mel@csn.ul.ie> wrote: >> >>> When a page is allocated, the page-flags >>> are updated with a value indicating it's type of reclaimability so that it >>> is placed on the correct list on free. >> >> We're getting awful tight on page-flags. >> >> Would it be possible to avoid adding the flag? Say, have a per-zone bitmap >> of size (zone->present_pages/(1<<MAX_ORDER)) bits, then do a lookup in >> there to work out whether a particular page is within a MAX_ORDER clump of >> easy-reclaimable pages? > > That would not actually work, the fallback allocation path can move > blocks smaller than MAX_ORDER to another recaim type. >
Believe it or not, it may be desirably to have a whole block represented by one or two bits. If a fallback allocation occurs and I move blocks between lists, I want pages that free later to be freed to the new list as well. Currently that doesn't happen because the flags are set per-page but it used to happen in an early version of anti-frag.
> But yeah, page flags are getting right, perhaps Rafael can use his > recently introduced bitmaps to rid us of the swsusp flags? > >
-- 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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