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 diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
  23 index 8d5b475..f5bc1b2 100644
  24 --- a/arch/powerpc/mm/hash_utils_64.c
  25 +++ b/arch/powerpc/mm/hash_utils_64.c
  26 @@ -516,7 +516,7 @@ static int __init htab_dt_scan_pftsize(unsigned long node,
  27
  28  static unsigned long __init htab_get_table_size(void)
  29  {
  30 -       unsigned long mem_size, rnd_mem_size, pteg_count;
  31 +       unsigned long mem_size, rnd_mem_size, pteg_count, psize;
  32
  33         /* If hash size isn't already provided by the platform, we try to
  34          * retrieve it from the device-tree. If it's not there neither, we
  35 @@ -534,7 +534,8 @@ static unsigned long __init htab_get_table_size(void)
  36                 rnd_mem_size <<= 1;
  37
  38         /* # pages / 2 */
  39 -       pteg_count = max(rnd_mem_size >> (12 + 1), 1UL << 11);
  40 +       psize = mmu_psize_defs[mmu_virtual_psize].shift;
  41 +       pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11);
  42
  43         return pteg_count << 7;
  44  }