Bug#1029484: linux: Enable Intel Uncore frequency control driver

[Miguel Bernal Marin]

Source: linux
Version: 6.1.7-1
Severity: wishlist
X-Debbugs-Cc: miguel.be...@linux.intel.com, jair.de.jesus.go...@intel.com

Dear Maintainer,

Please enable the Intel Uncore frequency control driver.
This driver allows control of uncore frequency limits on
supported server platforms.

# Intel Uncore frequency control driver

CONFIG_INTEL_UNCORE_FREQ_CONTROL=m

Some server users set limits on the uncore frequency using MSR 620H, while
running latency sensitive workloads. This driver "the uncore frequency",
controls RING/LLC (last-level cache) clocks.

But MSR control is not always possible from the user space, so this driver
provides a sysfs interface to set max and min frequency limits. This MSR
620H is a die scoped in multi-die system or package scoped in non multi-die
systems.

When this driver is loaded, a new directory is created under
/sys/devices/system/cpu.

For example on a two package Skylake server:
$ cd /sys/devices/system/cpu/intel_uncore_frequency

$ ls
package_00_die_00 package_01_die_00

$ ls package_00_die_00
max_freq_khz min_freq_khz initial_max_freq_khz
initial_min_freq_khz

$ grep . *
max_freq_khz:2400000
min_freq_khz:1200000
initial_max_freq_khz:2400000
initial_min_freq_khz:1200000

Here, initial_max_freq_khz and initial_min_freq_khz are read only
attributes to show power up or initial values of max and min frequencies
respectively. Other attributes are read-write, so that users can modify.

A merge request was created at:

https://salsa.debian.org/kernel-team/linux/-/merge_requests/645

Thanks,
Miguel