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| author | Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> | 2016-04-28 01:48:06 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-04-28 02:01:39 +0300 |
| commit | 9522a2ff9cde26ef48c30e0c9ca9ae4dfb669764 (patch) | |
| tree | 897b9d98dd831b2b6cc5d4fe0954840a9eae45d5 /Documentation/kernel-parameters.txt | |
| parent | eaa2c3aeef83f096cd1ec73df1310712e423337b (diff) | |
| download | linux-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.txt | 2 |
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) |