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Message-ID: <4A081A4B.1000204@linux.vnet.ibm.com>
Date: Mon, 11 May 2009 18:00:03 +0530
From: Mahesh Jagannath Salgaonkar <mahesh@...ux.vnet.ibm.com>
To: Linux Kernel <linux-kernel@...r.kernel.org>,
Suresh B Siddha <suresh.b.siddha@...el.com>,
Ingo Molnar <mingo@...e.hu>,
Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
CC: svaidy@...ux.vnet.ibm.com, Peter Zijlstra <a.p.zijlstra@...llo.nl>,
mahesh@...ux.vnet.ibm.com
Subject: [PATCH][REPOST] Don't export sched_mc_power_savings on multi-socket
single core system
My previous post got lost somewhere in lkml list. Hence reposting this
patch again.
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@...ux.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 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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