path: root/mm/vmstat.c
diff options
authorMel Gorman <mel@csn.ul.ie>2010-05-24 14:32:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-25 08:06:59 -0700
commit56de7263fcf3eb10c8dcdf8d59a9cec831795f3f (patch)
tree164637c0b678e20adfdcec4129563d9234faf405 /mm/vmstat.c
parented4a6d7f0676db50b5023cc01f6cda82a2f2a307 (diff)
mm: compaction: direct compact when a high-order allocation fails
Ordinarily when a high-order allocation fails, direct reclaim is entered to free pages to satisfy the allocation. With this patch, it is determined if an allocation failed due to external fragmentation instead of low memory and if so, the calling process will compact until a suitable page is freed. Compaction by moving pages in memory is considerably cheaper than paging out to disk and works where there are locked pages or no swap. If compaction fails to free a page of a suitable size, then reclaim will still occur. Direct compaction returns as soon as possible. As each block is compacted, it is checked if a suitable page has been freed and if so, it returns. [akpm@linux-foundation.org: Fix build errors] [aarcange@redhat.com: fix count_vm_event preempt in memory compaction direct reclaim] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmstat.c')
1 files changed, 14 insertions, 2 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c
index c6aacf51b55..7759941d4e7 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -429,7 +429,7 @@ static void fill_contig_page_info(struct zone *zone,
* The value can be used to determine if page reclaim or compaction
* should be used
-int fragmentation_index(unsigned int order, struct contig_page_info *info)
+static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
unsigned long requested = 1UL << order;
@@ -448,6 +448,15 @@ int fragmentation_index(unsigned int order, struct contig_page_info *info)
return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
+/* Same as __fragmentation index but allocs contig_page_info on stack */
+int fragmentation_index(struct zone *zone, unsigned int order)
+ struct contig_page_info info;
+ fill_contig_page_info(zone, order, &info);
+ return __fragmentation_index(order, &info);
#if defined(CONFIG_PROC_FS) || defined(CONFIG_COMPACTION)
@@ -771,6 +780,9 @@ static const char * const vmstat_text[] = {
+ "compact_stall",
+ "compact_fail",
+ "compact_success",
@@ -1136,7 +1148,7 @@ static void extfrag_show_print(struct seq_file *m,
for (order = 0; order < MAX_ORDER; ++order) {
fill_contig_page_info(zone, order, &info);
- index = fragmentation_index(order, &info);
+ index = __fragmentation_index(order, &info);
seq_printf(m, "%d.%03d ", index / 1000, index % 1000);