[PATCH] sched: add option to serialize load balancing

Large sched domains can be very expensive to scan.  Add an option SD_SERIALIZE
to the sched domain flags.  If that flag is set then we make sure that no
other such domain is being balanced.

[akpm@osdl.org: build fix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1208feab46e0..ea92e5c89089 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -648,6 +648,7 @@ enum idle_type
 #define SD_SHARE_CPUPOWER       128     /* Domain members share cpu power */
 #define SD_POWERSAVINGS_BALANCE 256     /* Balance for power savings */
 #define SD_SHARE_PKG_RESOURCES  512     /* Domain members share cpu pkg resources */
+#define SD_SERIALIZE            1024    /* Only a single load balancing instance */
 
 #define BALANCE_FOR_MC_POWER    \
         (sched_smt_power_savings ? SD_POWERSAVINGS_BALANCE : 0)