[tip:sched/core] sched: Don't export sched_mc_power_savings on multi-socket single core system

[tip-bot for Vaidyanathan Srinivasan]

Commit-ID:  2ff799d3cff1ecb274049378b28120ee5c1c5e5f
Gitweb:     http://git.kernel.org/tip/2ff799d3cff1ecb274049378b28120ee5c1c5e5f
Author:     Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 11 May 2009 20:09:14 +0530
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Mon, 11 May 2009 23:57:56 +0200

sched: Don't export sched_mc_power_savings on multi-socket single core system

Fix to prevent sched_mc_power_saving from being exported through sysfs
for multi-scoket single core system. Max cores should be always greater than
one (1). My earlier patch that introduced fix for not exporting
'sched_mc_power_saving' on laptops  broke it on multi-socket single core
system. This fix addresses issue on both laptop and multi-socket single
core system.
Below are the Test results:

1. Single socket - multi-core
       Before Patch: Does not export 'sched_mc_power_saving'
       After Patch: Does not export 'sched_mc_power_saving'
       Result: Pass

2. Multi Socket - single core
      Before Patch: exports 'sched_mc_power_saving'
      After Patch: Does not export 'sched_mc_power_saving'
      Result: Pass

3. Multi Socket - Multi core
      Before Patch: exports 'sched_mc_power_saving'
      After Patch: exports 'sched_mc_power_saving'

[ Impact: make the sched_mc_power_saving control available more consistently ]

Signed-off-by: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx>
Cc: Suresh B Siddha <suresh.b.siddha@xxxxxxxxx>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
LKML-Reference: <20090511143914.GB4853@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 arch/x86/include/asm/topology.h |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index f44b49a..066ef59 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -203,7 +203,8 @@ struct pci_bus;
 void x86_pci_root_bus_res_quirks(struct pci_bus *b);
 
 #ifdef CONFIG_SMP
-#define mc_capable()	(cpumask_weight(cpu_core_mask(0)) != nr_cpu_ids)
+#define mc_capable()	((boot_cpu_data.x86_max_cores > 1) && \
+			(cpumask_weight(cpu_core_mask(0)) != nr_cpu_ids))
 #define smt_capable()			(smp_num_siblings > 1)
 #endif
 
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