From 02c6de8d757cb32c0829a45d81c3dfcbcafd998b Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 8 Oct 2012 16:31:55 -0700 Subject: mm: cma: discard clean pages during contiguous allocation instead of migration Drop clean cache pages instead of migration during alloc_contig_range() to minimise allocation latency by reducing the amount of migration that is necessary. It's useful for CMA because latency of migration is more important than evicting the background process's working set. In addition, as pages are reclaimed then fewer free pages for migration targets are required so it avoids memory reclaiming to get free pages, which is a contributory factor to increased latency. I measured elapsed time of __alloc_contig_migrate_range() which migrates 10M in 40M movable zone in QEMU machine. Before - 146ms, After - 7ms [akpm@linux-foundation.org: fix nommu build] Signed-off-by: Mel Gorman Signed-off-by: Minchan Kim Reviewed-by: Mel Gorman Cc: Marek Szyprowski Acked-by: Michal Nazarewicz Cc: Rik van Riel Tested-by: Kyungmin Park Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/internal.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm/internal.h') diff --git a/mm/internal.h b/mm/internal.h index bbd7b34db4ea..8312d4fadf59 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -356,5 +356,6 @@ extern unsigned long vm_mmap_pgoff(struct file *, unsigned long, unsigned long, unsigned long); extern void set_pageblock_order(void); - +unsigned long reclaim_clean_pages_from_list(struct zone *zone, + struct list_head *page_list); #endif /* __MM_INTERNAL_H */ -- cgit v1.2.2