src/patches/suse-2.6.27.31/patches.arch/ppc64-reduce-hashtable-size-for-64k-pages.patch

   1 From: Anton Blanchard <anton@samba.org>
   2 Subject: powerpc/mm: Reduce hashtable size when using 64kB pages
   3 Date:   Fri Feb 13 11:57:30 2009 +0000
   4 References: bnc#501160
   5 Patch-upstream: yes
   6 Git: 13870b657578bcce167978ee93dc02bf54e3beb0
   7
   8     powerpc/mm: Reduce hashtable size when using 64kB pages
   9
  10     At the moment we size the hashtable based on 4kB pages / 2, even on a
  11     64kB kernel. This results in a hashtable that is much larger than it
  12     needs to be.
  13
  14     Grab the real page size and size the hashtable based on that
  15
  16     Note: This only has effect on non hypervisor machines.
  17
  18     Signed-off-by: Anton Blanchard <anton@samba.org>
  19     Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
  20 Acked-by: Nick Piggin <npiggin@suse.de>
  21
  22 ---
  23  arch/powerpc/mm/hash_utils_64.c |    5 +++--
  24  1 file changed, 3 insertions(+), 2 deletions(-)
  25
  26 --- a/arch/powerpc/mm/hash_utils_64.c
  27 +++ b/arch/powerpc/mm/hash_utils_64.c
  28 @@ -514,7 +514,7 @@ static int __init htab_dt_scan_pftsize(u
  29
  30  static unsigned long __init htab_get_table_size(void)
  31  {
  32 -       unsigned long mem_size, rnd_mem_size, pteg_count;
  33 +       unsigned long mem_size, rnd_mem_size, pteg_count, psize;
  34
  35         /* If hash size isn't already provided by the platform, we try to
  36          * retrieve it from the device-tree. If it's not there neither, we
  37 @@ -532,7 +532,8 @@ static unsigned long __init htab_get_tab
  38                 rnd_mem_size <<= 1;
  39
  40         /* # pages / 2 */
  41 -       pteg_count = max(rnd_mem_size >> (12 + 1), 1UL << 11);
  42 +       psize = mmu_psize_defs[mmu_virtual_psize].shift;
  43 +       pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11);
  44
  45         return pteg_count << 7;
  46  }