Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=64c5e135bf5a2a7f0ededb3435a31adbe0202f0c
Commit:     64c5e135bf5a2a7f0ededb3435a31adbe0202f0c
Parent:     ac0e5b7a6b93fb291b01fe1e951e3c16bcdd3503
Author:     Mel Gorman <[EMAIL PROTECTED]>
AuthorDate: Tue Oct 16 01:25:59 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Oct 16 09:43:00 2007 -0700

    don't group high order atomic allocations
    
    Grouping high-order atomic allocations together was intended to allow
    bursty users of atomic allocations to work such as e1000 in situations
    where their preallocated buffers were depleted.  This did not work in at
    least one case with a wireless network adapter needing order-1 allocations
    frequently.  To resolve that, the free pages used for min_free_kbytes were
    moved to separate contiguous blocks with the patch
    
bias-the-location-of-pages-freed-for-min_free_kbytes-in-the-same-max_order_nr_pages-blocks.
    
    It is felt that keeping the free pages in the same contiguous blocks should
    be sufficient for bursty short-lived high-order atomic allocations to
    succeed, maybe even with the e1000.  Even if there is a failure, increasing
    the value of min_free_kbytes will free pages as contiguous bloks in
    contrast to the standard buddy allocator which makes no attempt to keep the
    minimum number of free pages contiguous.
    
    This patch backs out grouping high order atomic allocations together to
    determine if it is really needed or not.  If a new report comes in about
    high-order atomic allocations failing, the feature can be reintroduced to
    determine if it fixes the problem or not.  As a side-effect, this patch
    reduces by 1 the number of bits required to track the mobility type of
    pages within a MAX_ORDER_NR_PAGES block.
    
    Signed-off-by: Mel Gorman <[EMAIL PROTECTED]>
    Acked-by: Andy Whitcroft <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 include/linux/mmzone.h          |    5 ++---
 include/linux/pageblock-flags.h |    2 +-
 mm/page_alloc.c                 |   37 +++++++------------------------------
 3 files changed, 10 insertions(+), 34 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 09b2c4f..fef08c6 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -36,9 +36,8 @@
 #define MIGRATE_UNMOVABLE     0
 #define MIGRATE_RECLAIMABLE   1
 #define MIGRATE_MOVABLE       2
-#define MIGRATE_HIGHATOMIC    3
-#define MIGRATE_RESERVE       4
-#define MIGRATE_TYPES         5
+#define MIGRATE_RESERVE       3
+#define MIGRATE_TYPES         4
 
 #define for_each_migratetype_order(order, type) \
        for (order = 0; order < MAX_ORDER; order++) \
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index fa3b100..5456da6 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -31,7 +31,7 @@
 
 /* Bit indices that affect a whole block of pages */
 enum pageblock_bits {
-       PB_range(PB_migrate, 3), /* 3 bits required for migrate types */
+       PB_range(PB_migrate, 2), /* 2 bits required for migrate types */
        NR_PAGEBLOCK_BITS
 };
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8aec4d4..ac8fc51 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -174,18 +174,13 @@ static void set_pageblock_migratetype(struct page *page, 
int migratetype)
                                        PB_migrate, PB_migrate_end);
 }
 
-static inline int allocflags_to_migratetype(gfp_t gfp_flags, int order)
+static inline int allocflags_to_migratetype(gfp_t gfp_flags)
 {
        WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
 
        if (unlikely(page_group_by_mobility_disabled))
                return MIGRATE_UNMOVABLE;
 
-       /* 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);
@@ -706,11 +701,10 @@ static struct page *__rmqueue_smallest(struct zone *zone, 
unsigned int order,
  * 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_HIGHATOMIC, MIGRATE_RESERVE },
-       [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,   
MIGRATE_HIGHATOMIC, MIGRATE_RESERVE },
-       [MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, 
MIGRATE_HIGHATOMIC, MIGRATE_RESERVE },
-       [MIGRATE_HIGHATOMIC]  = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, 
MIGRATE_MOVABLE,    MIGRATE_RESERVE },
-       [MIGRATE_RESERVE]     = { MIGRATE_RESERVE,     MIGRATE_RESERVE,   
MIGRATE_RESERVE,    MIGRATE_RESERVE }, /* Never used */
+       [MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,   
MIGRATE_RESERVE },
+       [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,   
MIGRATE_RESERVE },
+       [MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, 
MIGRATE_RESERVE },
+       [MIGRATE_RESERVE]     = { MIGRATE_RESERVE,     MIGRATE_RESERVE,   
MIGRATE_RESERVE }, /* Never used */
 };
 
 /*
@@ -804,9 +798,7 @@ 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) {
@@ -816,14 +808,6 @@ retry:
                        /* MIGRATE_RESERVE handled later if necessary */
                        if (migratetype == MIGRATE_RESERVE)
                                continue;
-                       /*
-                        * 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]))
@@ -849,8 +833,7 @@ retry:
                                                                
start_migratetype);
 
                                /* Claim the whole block if over half of it is 
free */
-                               if ((pages << current_order) >= (1 << 
(MAX_ORDER-2)) &&
-                                               migratetype != 
MIGRATE_HIGHATOMIC)
+                               if ((pages << current_order) >= (1 << 
(MAX_ORDER-2)))
                                        set_pageblock_migratetype(page,
                                                                
start_migratetype);
 
@@ -872,12 +855,6 @@ retry:
                }
        }
 
-       /* Allow fallback to high-order atomic blocks if memory is that low */
-       if (!nonatomic_fallback_atomic) {
-               nonatomic_fallback_atomic = 1;
-               goto retry;
-       }
-
        /* Use MIGRATE_RESERVE rather than fail an allocation */
        return __rmqueue_smallest(zone, order, MIGRATE_RESERVE);
 }
@@ -1112,7 +1089,7 @@ static struct page *buffered_rmqueue(struct zonelist 
*zonelist,
        struct page *page;
        int cold = !!(gfp_flags & __GFP_COLD);
        int cpu;
-       int migratetype = allocflags_to_migratetype(gfp_flags, order);
+       int migratetype = allocflags_to_migratetype(gfp_flags);
 
 again:
        cpu  = get_cpu();
-
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