target/linux/goldfish/patches-2.6.30/0056-mm-Check-if-any-page-in-a-pageblock-is-reserved-bef.patch

   1 From a4eb204a8029320c2dd748daf4f51fd48d337c3d Mon Sep 17 00:00:00 2001
   2 From: =?utf-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= <arve@android.com>
   3 Date: Wed, 18 Mar 2009 17:27:31 -0700
   4 Subject: [PATCH 056/134] mm: Check if any page in a pageblock is reserved before marking it MIGRATE_RESERVE
   5
   6 This fixes a problem where the first pageblock got marked MIGRATE_RESERVE even
   7 though it only had a few free pages. This in turn caused no contiguous memory
   8 to be reserved and frequent kswapd wakeups that emptied the caches to get more
   9 contiguous memory.
  10 ---
  11  mm/page_alloc.c |   16 +++++++++++++++-
  12  1 files changed, 15 insertions(+), 1 deletions(-)
  13
  14 --- a/mm/page_alloc.c
  15 +++ b/mm/page_alloc.c
  16 @@ -2570,6 +2570,20 @@ static inline unsigned long wait_table_b
  17  #define LONG_ALIGN(x) (((x)+(sizeof(long))-1)&~((sizeof(long))-1))
  18
  19  /*
  20 + * Check if a pageblock contains reserved pages
  21 + */
  22 +static int pageblock_is_reserved(unsigned long start_pfn)
  23 +{
  24 +       unsigned long end_pfn = start_pfn + pageblock_nr_pages;
  25 +       unsigned long pfn;
  26 +
  27 +       for (pfn = start_pfn; pfn < end_pfn; pfn++)
  28 +               if (PageReserved(pfn_to_page(pfn)))
  29 +                       return 1;
  30 +       return 0;
  31 +}
  32 +
  33 +/*
  34   * Mark a number of pageblocks as MIGRATE_RESERVE. The number
  35   * of blocks reserved is based on zone->pages_min. The memory within the
  36   * reserve will tend to store contiguous free pages. Setting min_free_kbytes
  37 @@ -2598,7 +2612,7 @@ static void setup_zone_migrate_reserve(s
  38                         continue;
  39
  40                 /* Blocks with reserved pages will never free, skip them. */
  41 -               if (PageReserved(page))
  42 +               if (pageblock_is_reserved(pfn))
  43                         continue;
  44
  45                 block_migratetype = get_pageblock_migratetype(page);