Re: [PATCH 2/2] PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS sysfs interface

From: Hannes Reinecke
Date: Fri Mar 22 2019 - 05:04:00 EST

On 3/21/19 11:20 PM, Rafael J. Wysocki wrote:
From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

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@xxxxxxxxx>
Documentation/ABI/testing/sysfs-devices-system-cpu | 18 ++++
Documentation/admin-guide/pm/intel_epb.rst | 27 ++++++
arch/x86/kernel/cpu/intel_epb.c | 93 ++++++++++++++++++++-
3 files changed, 134 insertions(+), 4 deletions(-)

Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>


Dr. Hannes Reinecke Teamlead Storage & Networking
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