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authorMel Gorman <mel@csn.ul.ie>2007-10-16 01:25:53 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-16 09:43:00 -0700
commite010487dbe09d63cf916fd1b119d17abd0f48207 (patch)
tree37c7f36913daf4bc0a68a1d0ba1cc30ee0d4e307 /mm
parente12ba74d8ff3e2f73a583500d7095e406df4d093 (diff)
downloadlwn-e010487dbe09d63cf916fd1b119d17abd0f48207.tar.gz
lwn-e010487dbe09d63cf916fd1b119d17abd0f48207.zip
Group high-order atomic allocations
In rare cases, the kernel needs to allocate a high-order block of pages without sleeping. For example, this is the case with e1000 cards configured to use jumbo frames. Migrating or reclaiming pages in this situation is not an option. This patch groups these allocations together as much as possible by adding a new MIGRATE_TYPE. The MIGRATE_HIGHATOMIC type are exactly what they sound like. Care is taken that pages of other migrate types do not use the same blocks as high-order atomic allocations. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c36
1 files changed, 30 insertions, 6 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 29f4de1423c9..03fef8d987f6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -170,10 +170,16 @@ static void set_pageblock_migratetype(struct page *page, int migratetype)
PB_migrate, PB_migrate_end);
}
-static inline int gfpflags_to_migratetype(gfp_t gfp_flags)
+static inline int allocflags_to_migratetype(gfp_t gfp_flags, int order)
{
WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
+ /* Cluster high-order atomic allocations together */
+ if (unlikely(order > 0) &&
+ (!(gfp_flags & __GFP_WAIT) || in_interrupt()))
+ return MIGRATE_HIGHATOMIC;
+
+ /* Cluster based on mobility */
return (((gfp_flags & __GFP_MOVABLE) != 0) << 1) |
((gfp_flags & __GFP_RECLAIMABLE) != 0);
}
@@ -188,7 +194,7 @@ static void set_pageblock_migratetype(struct page *page, int migratetype)
{
}
-static inline int gfpflags_to_migratetype(gfp_t gfp_flags)
+static inline int allocflags_to_migratetype(gfp_t gfp_flags, int order)
{
return MIGRATE_UNMOVABLE;
}
@@ -679,9 +685,10 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
* the free lists for the desirable migrate type are depleted
*/
static int fallbacks[MIGRATE_TYPES][MIGRATE_TYPES-1] = {
- [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE },
- [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE },
- [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE },
+ [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_HIGHATOMIC },
+ [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_HIGHATOMIC },
+ [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE,MIGRATE_HIGHATOMIC },
+ [MIGRATE_HIGHATOMIC] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE,MIGRATE_MOVABLE},
};
/*
@@ -758,13 +765,24 @@ static struct page *__rmqueue_fallback(struct zone *zone, int order,
int current_order;
struct page *page;
int migratetype, i;
+ int nonatomic_fallback_atomic = 0;
+retry:
/* Find the largest possible block of pages in the other list */
for (current_order = MAX_ORDER-1; current_order >= order;
--current_order) {
for (i = 0; i < MIGRATE_TYPES - 1; i++) {
migratetype = fallbacks[start_migratetype][i];
+ /*
+ * Make it hard to fallback to blocks used for
+ * high-order atomic allocations
+ */
+ if (migratetype == MIGRATE_HIGHATOMIC &&
+ start_migratetype != MIGRATE_UNMOVABLE &&
+ !nonatomic_fallback_atomic)
+ continue;
+
area = &(zone->free_area[current_order]);
if (list_empty(&area->free_list[migratetype]))
continue;
@@ -797,6 +815,12 @@ static struct page *__rmqueue_fallback(struct zone *zone, int order,
}
}
+ /* Allow fallback to high-order atomic blocks if memory is that low */
+ if (!nonatomic_fallback_atomic) {
+ nonatomic_fallback_atomic = 1;
+ goto retry;
+ }
+
return NULL;
}
#else
@@ -1058,7 +1082,7 @@ static struct page *buffered_rmqueue(struct zonelist *zonelist,
struct page *page;
int cold = !!(gfp_flags & __GFP_COLD);
int cpu;
- int migratetype = gfpflags_to_migratetype(gfp_flags);
+ int migratetype = allocflags_to_migratetype(gfp_flags, order);
again:
cpu = get_cpu();