[PATCH] sched: mc/smt power savings sched policy

sysfs entries 'sched_mc_power_savings' and 'sched_smt_power_savings' in
/sys/devices/system/cpu/ control the MC/SMT power savings policy for the
scheduler.

Based on the values (1-enable, 0-disable) for these controls, sched groups
cpu power will be determined for different domains.  When power savings
policy is enabled and under light load conditions, scheduler will minimize
the physical packages/cpu cores carrying the load and thus conserving
power(with a perf impact based on the workload characteristics...  see OLS
2005 CMP kernel scheduler paper for more details..)

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Con Kolivas <kernel@kolivas.org>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/asm-i386/topology.h b/include/asm-i386/topology.h
index aa4185ee81fb..6adbd9b1ae88 100644
--- a/include/asm-i386/topology.h
+++ b/include/asm-i386/topology.h
@@ -112,4 +112,9 @@ extern unsigned long node_remap_size[];
 
 extern cpumask_t cpu_coregroup_map(int cpu);
 
+#ifdef CONFIG_SMP
+#define mc_capable()    (boot_cpu_data.x86_max_cores > 1)
+#define smt_capable()   (smp_num_siblings > 1)
+#endif
+
 #endif /* _ASM_I386_TOPOLOGY_H */