On Thu, Jan 26, 2012 at 10:00:50AM +0100, Marek Szyprowski wrote:
From: Michal Nazarewicz <mina86@xxxxxxxxxx>
@@ -875,10 +895,15 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
* This array describes the order lists are fallen back to when
* the free lists for the desirable migrate type are depleted
*/
-static int fallbacks[MIGRATE_TYPES][3] = {
+static int fallbacks[MIGRATE_TYPES][4] = {
[MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE },
[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE },
+#ifdef CONFIG_CMA
+ [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_CMA , MIGRATE_RESERVE },
On Mon, 30 Jan 2012 13:35:42 +0100, Mel Gorman <mel@xxxxxxxxx> wrote:
This is a curious choice. MIGRATE_CMA is allowed to contain movable
pages. By using MIGRATE_RECLAIMABLE and MIGRATE_UNMOVABLE for movable
pages instead of MIGRATE_CMA, you increase the changes that unmovable
pages will need to use MIGRATE_MOVABLE in the future which impacts
fragmentation avoidance. I would recommend that you change this to
{ MIGRATE_CMA, MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE }
At the beginning the idea was to try hard not to get pages from MIGRATE_CMA
allocated at all, thus it was put at the end of the fallbacks list, but on
a busy system this probably won't help anyway, so I'll change it per your
suggestion.
@@ -1017,11 +1049,14 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
rmv_page_order(page);
/* Take ownership for orders >= pageblock_order */
- if (current_order >= pageblock_order)
+ if (current_order >= pageblock_order &&
+ !is_pageblock_cma(page))
change_pageblock_range(page, current_order,
start_migratetype);
- expand(zone, page, order, current_order, area, migratetype);
+ expand(zone, page, order, current_order, area,
+ is_migrate_cma(start_migratetype)
+ ? start_migratetype : migratetype);
What is this check meant to be doing?
start_migratetype is determined by allocflags_to_migratetype() and
that never will be MIGRATE_CMA so is_migrate_cma(start_migratetype)
should always be false.
Right, thanks! This should be the other way around, ie.:
+ expand(zone, page, order, current_order, area,
+ is_migrate_cma(migratetype)
+ ? migratetype : start_migratetype);
I'll fix this and the calls to is_pageblock_cma().
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
ooo +----<email/xmpp: mpn@xxxxxxxxxx>--------------ooO--(_)--Ooo--
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