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Message-ID: <50212A05.2070503@redhat.com> Date: Tue, 07 Aug 2012 10:45:25 -0400 From: Rik van Riel <riel@...hat.com> To: Mel Gorman <mgorman@...e.de> CC: Linux-MM <linux-mm@...ck.org>, Minchan Kim <minchan@...nel.org>, Jim Schutt <jaschut@...dia.gov>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 6/6] mm: have order > 0 compaction start near a pageblock with free pages On 08/07/2012 08:31 AM, Mel Gorman wrote: > commit [7db8889a: mm: have order> 0 compaction start off where it left] > introduced a caching mechanism to reduce the amount work the free page > scanner does in compaction. However, it has a problem. Consider two process > simultaneously scanning free pages > > C > Process A M S F > |---------------------------------------| > Process B M FS Argh. Good spotting. > This is not optimal and it can still race but the compact_cached_free_pfn > will be pointing to or very near a pageblock with free pages. Agreed on the "not optimal", but I also cannot think of a better idea right now. Getting this fixed for 3.6 is important, we can think of future optimizations in San Diego. > Signed-off-by: Mel Gorman<mgorman@...e.de> Reviewed-by: Rik van Riel <riel@...hat.com> -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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