intel_pstate can be modified with service parameter
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
StarlingX |
In Progress
|
Undecided
|
Jiping Ma |
Bug Description
Brief Description
In Icelake server, isolcpu core frequeccy seem to cap to base frequency.
Ex: Machine with 2.0GHz , configure the node with,
Use Ice lake CPU.
Use low letancy
Set some cores are isolation core
Enanle K8S CPU manager as static ( I am not sure this is mandate to cuase this issue )
Then see each Core frequency, isolation core frequency seem to stick to "base frequency"
[root@applicati
cpu MHz : 3100.000
cpu MHz : 3100.000 <- Other cores showed turbo boosted frequency
cpu MHz : 3100.040 <- isol cpu. Stick to base frequench (2.0GHz)
cpu MHz : 2934.800 <- isol cpu. Stick to base frequench (2.0GHz)
cpu MHz : 2929.562
cpu MHz : 2936.802
cpu MHz : 2960.046
cpu MHz : 2920.794
[root@applicati
performance
[root@applicati
intel_pstate
[root@applicati
performance
[root@applicati
2000000 <- Same as base frequency
I executed "cpupower" command on isolated core, and noticed that cpupower failed to get frequency value from either HW and SW.
controller-
analyzing CPU 2:
driver: intel_pstate
CPUs which run at the same hardware frequency: 2
CPUs which need to have their frequency coordinated by software: 2
maximum transition latency: Cannot determine or is not supported.
hardware limits: 800 MHz - 3.10 GHz
available cpufreq governors: performance powersave
current policy: frequency should be within 800 MHz and 3.10 GHz.
current CPU frequency: Unable to call hardware <- Failed to get value from HW
current CPU frequency: Unable to call to kernel <- Failed to get value from SW
boost state support:
Supported: yes
Active: yes
From Ice Lake, HWP ( HardWare Pstate ) was introduced and enable by default. So I guess linux 5.10 failed to get value from HWP. So I am not sure whether "Actual frequency as down to 2.0GHz" or "It just a display issue".
Severity
Major: If actual frequency is set to base frequency.
Minor: When this is just display issue.
Steps to Reproduce{}
1: Use Icelake server such as CoyotePass.
2: Enable K8S CPU manager as "static"
3: Assign some core to "isolatec core"
4: Unlock host.
5: Check isolated core number.
6: Check core frequency with grep "cpu MHz" /proc/cpuinfo
-> Isolation core showed base frequency.
Expected Behavior
isolation cores's frequency are also turbo boosted.
Actual Behavior
isolation core's frequency is look like keep to set base frequency.
Reproducibility
Reproducible
System Configuration
Any configuration with low latency profile. ( standard profile does now show this issue. ) Only be happened with Ice lake based servers which has HWP (Hardware P-State ) feature.
Load info (eg: 2022-03-
N/A
Last Pass
N/A
Alarms
No alarms
Test Activity
N/A
Workaround
Disable HWP based p-state with kernel command such as intel_pstate=no_hwp or intel_pstate=
Ex:
controller-
BOOT_IMAGE=
As a result, isolation core's frequency seemed also turbo boosted.
[root@isolated-
cpu MHz : 2899.990
cpu MHz : 2899.991
cpu MHz : 3500.000 <- isolated core
cpu MHz : 2900.074 <- isolated core
cpu MHz : 2900.020
cpu MHz : 2899.992
But I am not sure how to persist this setting.
Changed in starlingx: | |
assignee: | nobody → Jiping Ma (jma11) |
Fix proposed to branch: master /review. opendev. org/c/starlingx /stx-puppet/ +/880712
Review: https:/