Bug 1241815

Summary:	"powersave" profile makes network unstable
Product:	[Fedora] Fedora	Reporter:	Tomasz Torcz <tomek>
Component:	tuned	Assignee:	Jaroslav Škarvada <jskarvad>
Status:	CLOSED EOL	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	22	CC:	jskarvad, jv+fedora, pknirsch, twoerner
Target Milestone:	---
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Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-07-19 15:17:05 UTC	Type:	Bug
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Embargoed:

Description Tomasz Torcz 2015-07-10 07:35:03 UTC

Description of problem:
After enabling "powersave" profile, network interface very often loses link for 1.5-2.5 seconds. On profile "balance" network is stable.

[1713411.927023] r8169 0000:04:00.0 enp4s0: link down
[1713411.927090] lan: port 1(enp4s0) entered disabled state
[1713411.940953] r8169 0000:05:00.0 enp5s0: link down 
[1713413.438907] r8169 0000:05:00.0 enp5s0: link up
[1713414.297172] r8169 0000:04:00.0 enp4s0: link up


Version-Release number of selected component (if applicable):
tuned-2.4.1-5.fc22.noarch
kernel-4.0.5-300.fc22.x86_64


Steps to Reproduce:
1. tunedadm profile powersave
2. observe link flapping
3. tuneadm profile balanced
4. link does not flap


Additional info:
I did not found anything obvious wrt network configuration in "powersave" profile definition.

I previously reported the bug against kernel:
https://bugzilla.redhat.com/show_bug.cgi?id=1151865                                                                                                                                                                                                                               
Just now I found tuned profile link.

Comment 1 Jaroslav Škarvada 2015-07-10 09:35:55 UTC

Hi, this is probably caused by dynamic tuning switching network interface speed according to its utilization. You can switch it globally off by setting:

dynamic_tuning = 0

in /etc/tuned/tuned-main.conf. AFAIK it can save few mW of energy, but it can also cause trouble with some network adapters. In next tuned release (hopefully 2.6) there is planned more fine grained configuration option which should allow switching it off only for network plugin.

Comment 2 Tomasz Torcz 2015-07-10 15:20:45 UTC

Bingo! After disabling dynamic tuning link no longer flaps (no matter which profile is selected). Thank you.

Comment 3 Fedora End Of Life 2016-07-19 15:17:05 UTC

Fedora 22 changed to end-of-life (EOL) status on 2016-07-19. Fedora 22 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

If you can reproduce this bug against a currently maintained version of
Fedora please feel free to reopen this bug against that version. If you
are unable to reopen this bug, please file a new report against the
current release. If you experience problems, please add a comment to this
bug.

Thank you for reporting this bug and we are sorry it could not be fixed.