[PATCH] Don't export sched_mc_power_savings on multi-socket single core system

[PATCH] Don't export sched_mc_power_savings on multi-socket single core system

[Mahesh Jagannath Salgaonkar]

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'


Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>

Index: linux-2.6/arch/x86/include/asm/topology.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/topology.h
+++ linux-2.6/arch/x86/include/asm/topology.h
@@ -203,7 +203,8 @@ struct pci_bus;
 void set_pci_bus_resources_arch_default(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

Re: [PATCH] Don't export sched_mc_power_savings on multi-socket single core system

[Ingo Molnar]

* Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com> wrote:

> 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:

> +#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)

patch looks good but is whitespace damaged (all tabs were converted 
to spaces). See Documentation/email-clients.txt about how to set up 
your client.

	Ingo