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authorLen Brown <len.brown@intel.com>2011-01-18 20:48:27 -0500
committerLen Brown <len.brown@intel.com>2011-02-17 17:08:46 -0500
commit14796fca2bd22acc73dd0887248d003b0f441d08 (patch)
tree45281c00405077fe1a099d585588d2173ee90fea /arch
parent100b33c8bd8a3235fd0b7948338d6cbb3db3c63d (diff)
downloadop-kernel-dev-14796fca2bd22acc73dd0887248d003b0f441d08.zip
op-kernel-dev-14796fca2bd22acc73dd0887248d003b0f441d08.tar.gz
intel_idle: disable NHM/WSM HW C-state auto-demotion
Hardware C-state auto-demotion is a mechanism where the HW overrides the OS C-state request, instead demoting to a shallower state, which is less expensive, but saves less power. Modern Linux should generally get exactly the states it requests. In particular, when a CPU is taken off-line, it must not be demoted, else it can prevent the entire package from reaching deep C-states. https://bugzilla.kernel.org/show_bug.cgi?id=25252 Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/msr-index.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 4d0dfa0..b75eeab 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -36,6 +36,10 @@
#define MSR_IA32_PERFCTR1 0x000000c2
#define MSR_FSB_FREQ 0x000000cd
+#define MSR_NHM_SNB_PKG_CST_CFG_CTL 0x000000e2
+#define NHM_C3_AUTO_DEMOTE (1UL << 25)
+#define NHM_C1_AUTO_DEMOTE (1UL << 26)
+
#define MSR_MTRRcap 0x000000fe
#define MSR_IA32_BBL_CR_CTL 0x00000119
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