ACK: [SRU J/L/M][PATCH 0/1] Unable to Interpret the Frequency Values in Cpuinfo_min_freq and Cpuino_max_freq Sysfs Files

[Roxana Nicolescu]

On 10/08/2023 18:48, Michael Reed wrote:
> From: Michael Reed <Michael.Reed at canonical.com>
>
> BugLink: https://bugs.launchpad.net/bugs/2030924
>
> SRU Justification:
>
> [Impact]
>
> On DELL EMC PowerEdge system when Ubuntu 22.04.1 OS is Installed, Unable to Interpret the values in cpuinfo_max_freq and cpuinfo_min_freq sysfs files as per the Intel specs document.
>
> Steps to Reproduce:
>
> 1. Install one CPU that supports DBS "Demand-Based Power Management".
> 2. Install Ubuntu 22.04.1 OS.
> 2. Enable "Logical Processor" under CPU Information menu from F2 setup.
> 3. Save changes and reboot to Ubuntu 22.04.1 OS.
> 4. Right click on "Computer" and select "File system" and check for the following CPU directories.
>
>     /sys/devices/system/cpu/cpu0/cpufreq/cpu0
>     /sys/devices/system/cpu/cpu0/cpufreq/cpu1
>
> 5. View the Max Frequency and Min Frequency under CPU0 and CPU1 directory.
> 6. The Max and Min Frequency did not match as per the Intel specs datasheet.
>
> Actual results:
>
>   /sys/devices/system/cpu/cpu0/cpufreq/cpu0/cpuinfo_max_freq -> 6800000
>   /sys/devices/system/cpu/cpu0/cpufreq/cpu0/cpuinfo_min_freq -> 800000
>   /sys/devices/system/cpu/cpu0/cpufreq/cpu0/base_frequency -> 3900000
>
>   Expected results: As per Intel datasheet specification.
>
>   /sys/devices/system/cpu/cpu0/cpufreq/cpu0/cpuinfo_max_freq -> 5300 MHz
>   /sys/devices/system/cpu/cpu0/cpufreq/cpu0/cpuinfo_min_freq -> 800 MHz
>   /sys/devices/system/cpu/cpu0/cpufreq/cpu0/base_frequency -> 3000 MHz
>
> [Fix]
> cpufreq: intel_pstate: Fix scaling for hybrid-capable systems with disabled E-cores
> https://github.com/torvalds/linux/commit/0fcfc9e51990246a9813475716746ff5eb98c6aa [github.com]
>
> [Test Plan]
>
> Same as steps to reproduce
>
> [ Where problems could occur ]
>
> This issue is seen on Intel based system under development which supports DBS "Demand-Based Power Management", then install Ubuntu-22.04 and boot into OS then
> check for the frequency values under /sys/devices/system/cpu/cpu0/cpufreq/cpu0
> Regression risk = Low to medium
>
> [ Other Info ]
>
> Jammy
> https://code.launchpad.net/~mreed8855/ubuntu/+source/linux/+git/jammy/+ref/cpuinfo_freq
>
> lunar
> https://code.launchpad.net/~mreed8855/ubuntu/+source/linux/+git/lunar/+ref/cpuinfo_freq_lunar_2
>
> Mantic
> https://code.launchpad.net/~mreed8855/ubuntu/+source/linux/+git/mantic/+ref/cpuinfo_freq_mantic
>
>
> Srinivas Pandruvada (1):
>    cpufreq: intel_pstate: Fix scaling for hybrid-capable systems with
>      disabled E-cores
>
>   drivers/cpufreq/intel_pstate.c | 58 ++++++++++++++++++++++++++++------
>   1 file changed, 48 insertions(+), 10 deletions(-)
>
Acked-by: Roxana Nicolescu <roxana.nicolescu at canonical.com>