[PATCH 03/04] Cpuset: mark number_of_cpusets read_mostly

[Paul Jackson <pj@sgi.com>]

Mark cpuset global 'number_of_cpusets' as __read_mostly.

This global is accessed everytime a zone is considered
in the zonelist loops beneath __alloc_pages, looking for
a free memory page.  If number_of_cpusets is just one,
then we can short circuit the mems_allowed check.

Since this global is read alot on a hot path, and written
rarely, it is an excellent candidate for __read_mostly.

Thanks to Christoph Lameter for the suggestion.

Signed-off-by: Paul Jackson <pj@sgi.com>

---

 kernel/cpuset.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

--- 2.6.15-rc3-mm1.orig/kernel/cpuset.c	2005-12-13 18:08:26.644979252 -0800
+++ 2.6.15-rc3-mm1/kernel/cpuset.c	2005-12-13 18:09:55.658647865 -0800
@@ -62,7 +62,7 @@
  * When there is only one cpuset (the root cpuset) we can
  * short circuit some hooks.
  */
-int number_of_cpusets;
+int number_of_cpusets __read_mostly;
 
 /* See "Frequency meter" comments, below. */
 

-- 
                          I won't rest till it's the best ...
                          Programmer, Linux Scalability
                          Paul Jackson <pj@sgi.com> 1.650.933.1373
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