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Bug 2012226

Summary:	High cpu usage of cppc_fie even when idle
Product:	[Fedora] Fedora	Reporter:	russ.butler
Component:	kernel	Assignee:	Jeremy Linton (ARM) <jlinton>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	35	CC:	acaringi, adscvr, airlied, alciregi, bskeggs, hdegoede, jarodwilson, jeremy, jeremy.linton, jglisse, jonathan, josef, kernel-maint, lgoncalv, linville, masami256, mchehab, ptalbert, pwhalen, russ.butler, steved
Target Milestone:	---
Target Release:	---
Hardware:	aarch64
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2022-10-19 18:21:23 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	245418

Description russ.butler 2021-10-08 15:24:20 UTC

Description of problem:
High cpu usage of cppc_fie (1.5-2.5%) when idle

Version-Release number of selected component (if applicable):
Fedora Linux 35 (Server Edition Prerelease)


How reproducible:
CPU usage is constantly hovers between 1.5 and 2.5% - very reproducible.


Steps to Reproduce:
1. Install Fedora 35 server edition on an aarch64 Ampere Altra machine.
2. Use top to view that CPU usage


Actual results:
CPU usage is between 1.5% and 2.5% when the machine is idle


Expected results:
CPU usage is less than 0.75 1.5% and 2.5% when the machine is idle

Comment 1 Jeremy Linton 2021-10-14 20:04:56 UTC

Then this isn't specific to my hacked up rpi4 with unmerged TFA/uefi patches to enable CPPC. This might be pretty significant if it is not an accounting problem. I saw this in 5.14 and instrumented the cppc call path to see if it was making excessive mailbox inquiries and it didn't appear to be the case.

Comment 2 Jeremy Linton 2022-07-26 15:09:47 UTC

Fix posted: https://lkml.org/lkml/2022/7/26/679

(although thinking about it I probably should have hidden the module parm or at least flipped its value if FIE is disabled)

Comment 3 Jeremy Linton 2022-10-19 18:21:23 UTC

This is fixed closing.