On Fri, Apr 6, 2012 at 1:32 AM, Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> wrote:
In isolate_freepages() check each page in a pageblock
instead of checking only first pages of pageblock_nr_pages
intervals (suitable_migration_target(page) is called before
isolate_freepages_block() so if page is "unsuitable" whole
pageblock_nr_pages pages will be ommited from the check).
It greatly improves possibility of finding free pages to
isolate during compaction_alloc() phase.
I doubt how this can help keeping free pages.
Now, compaction works by pageblock_nr_pages unit so although you work by per page, all pages in a block would have same block type.
It means we can't pass suitable_migration_target. No?
Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
mm/compaction.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index d9ebebe..bc77135 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -65,7 +65,7 @@ static unsigned long isolate_freepages_block(struct zone *zone,
/* Get the last PFN we should scan for free pages at */
zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
- end_pfn = min(blockpfn + pageblock_nr_pages, zone_end_pfn);
+ end_pfn = min(blockpfn + 1, zone_end_pfn);
/* Find the first usable PFN in the block to initialse page cursor */
for (; blockpfn < end_pfn; blockpfn++) {
@@ -160,8 +160,7 @@ static void isolate_freepages(struct zone *zone,
* pages on cc->migratepages. We stop searching if the migrate
* and free page scanners meet or enough free pages are isolated.
*/
- for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
- pfn -= pageblock_nr_pages) {
+ for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages; pfn--) {
unsigned long isolated;
if (!pfn_valid(pfn))
--
1.7.9.4
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