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authorSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>2016-04-28 01:48:06 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-04-28 02:01:39 +0300
commit9522a2ff9cde26ef48c30e0c9ca9ae4dfb669764 (patch)
tree897b9d98dd831b2b6cc5d4fe0954840a9eae45d5 /Documentation/kernel-parameters.txt
parenteaa2c3aeef83f096cd1ec73df1310712e423337b (diff)
downloadlinux-9522a2ff9cde26ef48c30e0c9ca9ae4dfb669764.tar.xz
cpufreq: intel_pstate: Enforce _PPC limits
Use ACPI _PPC notification to limit max P state driver will request. ACPI _PPC change notification is sent by BIOS to limit max P state in several cases: - Reduce impact of platform thermal condition - When Config TDP feature is used, a changed _PPC is sent to follow TDP change - Remote node managers in server want to control platform power via baseboard management controller (BMC) This change registers with ACPI processor performance lib so that _PPC changes are notified to cpufreq core, which in turns will result in call to .setpolicy() callback. Also the way _PSS table identifies a turbo frequency is not compatible to max turbo frequency in intel_pstate, so the very first entry in _PSS needs to be adjusted. This feature can be turned on by using kernel parameters: intel_pstate=support_acpi_ppc Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> [ rjw: Minor cleanups ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt2
1 files changed, 2 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ecc74fa4bfde..31c094fb1141 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1661,6 +1661,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
hwp_only
Only load intel_pstate on systems which support
hardware P state control (HWP) if available.
+ support_acpi_ppc
+ Enforce ACPI _PPC performance limits.
intremap= [X86-64, Intel-IOMMU]
on enable Interrupt Remapping (default)