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authorAndy Whitcroft <apw@shadowen.org>2007-08-22 14:01:26 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-08-22 19:52:45 -0700
commitc661b078fd62abe06fd11fab4ac5e4eeafe26b6d (patch)
treef21ffeed682900b783563e7d8a8dde906706cc88 /kernel/time.c
parente9187bdcbbc06090757d565a3077e1b0ecab23d2 (diff)
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synchronous lumpy reclaim: wait for page writeback when directly reclaiming contiguous areas
Lumpy reclaim works by selecting a lead page from the LRU list and then selecting pages for reclaim from the order-aligned area of pages. In the situation were all pages in that region are inactive and not referenced by any process over time, it works well. In the situation where there is even light load on the system, the pages may not free quickly. Out of a area of 1024 pages, maybe only 950 of them are freed when the allocation attempt occurs because lumpy reclaim returned early. This patch alters the behaviour of direct reclaim for large contiguous blocks. The first attempt to call shrink_page_list() is asynchronous but if it fails, the pages are submitted a second time and the calling process waits for the IO to complete. This may stall allocators waiting for contiguous memory but that should be expected behaviour for high-order users. It is preferable behaviour to potentially queueing unnecessary areas for IO. Note that kswapd will not stall in this fashion. [apw@shadowen.org: update to version 2] [apw@shadowen.org: update to version 3] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/time.c')
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