path: root/mm/page_io.c
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authorVlastimil Babka <>2016-10-07 17:00:46 -0700
committerLinus Torvalds <>2016-10-07 18:46:29 -0700
commit20311420282f3402888f1d9b8b80d924d491aadf (patch)
tree6ef33e5e616118f2000188440290e52709a0d488 /mm/page_io.c
parentcc5c9f098fe48a8736add8a23c983524ca16cea5 (diff)
mm, compaction: restrict fragindex to costly orders
Fragmentation index and the vm.extfrag_threshold sysctl is meant as a heuristic to prevent excessive compaction for costly orders (i.e. THP). It's unlikely to make any difference for non-costly orders, especially with the default threshold. But we cannot afford any uncertainty for the non-costly orders where the only alternative to successful reclaim/compaction is OOM. After the recent patches we are guaranteed maximum effort without heuristics from compaction before deciding OOM, and fragindex is the last remaining heuristic. Therefore skip fragindex altogether for non-costly orders. Suggested-by: Michal Hocko <> Link: Signed-off-by: Vlastimil Babka <> Acked-by: Michal Hocko <> Cc: Mel Gorman <> Cc: Joonsoo Kim <> Cc: David Rientjes <> Cc: Rik van Riel <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/page_io.c')
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