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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-03-21 23:20:17 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-04-07 22:33:42 +0200 |
| commit | b9c273babce791cf228fc466577f55056a699f9c (patch) | |
| tree | ea9f1103024da00c2ee7804984cac36366cd43bc /Documentation/ABI | |
| parent | PM / arch: x86: Rework the MSR_IA32_ENERGY_PERF_BIAS handling (diff) | |
| download | linux-b9c273babce791cf228fc466577f55056a699f9c.tar.xz linux-b9c273babce791cf228fc466577f55056a699f9c.zip | |
PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS sysfs interface
The Performance and Energy Bias Hint (EPB) is expected to be set by
user space through the generic MSR interface, but that interface is
not particularly nice and there are security concerns regarding it,
so it is not always available.
For this reason, add a sysfs interface for reading and updating the
EPB, in the form of a new attribute, energy_perf_bias, located
under /sys/devices/system/cpu/cpu#/power/ for online CPUs that
support the EPB feature.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Acked-by: Borislav Petkov <bp@suse.de>
Diffstat (limited to 'Documentation/ABI')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-system-cpu | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index 9605dbd4b5b5..7f4af7da3fbc 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -518,3 +518,21 @@ Description: Control Symetric Multi Threading (SMT) If control status is "forceoff" or "notsupported" writes are rejected. + +What: /sys/devices/system/cpu/cpu#/power/energy_perf_bias +Date: March 2019 +Contact: linux-pm@vger.kernel.org +Description: Intel Energy and Performance Bias Hint (EPB) + + EPB for the given CPU in a sliding scale 0 - 15, where a value + of 0 corresponds to a hint preference for highest performance + and a value of 15 corresponds to the maximum energy savings. + + In order to change the EPB value for the CPU, write either + a number in the 0 - 15 sliding scale above, or one of the + strings: "performance", "balance-performance", "normal", + "balance-power", "power" (that represent values reflected by + their meaning), to this attribute. + + This attribute is present for all online CPUs supporting the + Intel EPB feature. |