Bug 1046021

Summary:	latencytop not enabled in kernel
Product:	[Fedora] Fedora	Reporter:	john.haxby <john.haxby>
Component:	kernel	Assignee:	Kernel Maintainer List <kernel-maint>
Status:	CLOSED DUPLICATE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	19	CC:	gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda
Target Milestone:	---
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2013-12-24 14:19:19 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:

Description john.haxby@oracle.com 2013-12-23 08:49:31 UTC

Description of problem:
latencytop reports the following when trying to start it:

  Failed to open /proc/latency_stats: No such file or directory
  Please enable the CONFIG_LATENCYTOP configuration in your kernel.

Version-Release number of selected component (if applicable): kernel-3.12.5-200.fc19.x86_64

How reproducible:
Always.

Steps to Reproduce:
1. Install latencytop.
2. Run latencytop.
3. See latencytop fail.
  
Actual results:
latencytop reports CONFIG_LATENCYTOP not enabled

Expected results:
latencytop starts to measure system latencies.

Additional info:

$ grep CONFIG_LATENCYTOP /boot/config-*
/boot/config-3.11.10-200.fc19.x86_64:# CONFIG_LATENCYTOP is not set
/boot/config-3.11.9-200.fc19.x86_64:# CONFIG_LATENCYTOP is not set
/boot/config-3.12.5-200.fc19.x86_64:# CONFIG_LATENCYTOP is not set

Comment 1 john.haxby@oracle.com 2013-12-23 09:18:02 UTC

For completeness:

$ grep CONFIG_LATENCYTOP ./boot/config-*
./boot/config-3.12.5-302.fc20.x86_64:# CONFIG_LATENCYTOP is not set
./boot/config-3.13.0-0.rc4.git5.1.fc21.x86_64:# CONFIG_LATENCYTOP is not set

Thse are the current and updatest-testing Fedora 20 kernels.  Feel free to convert this bug to Fedora 20 if it helps.

Comment 2 Josh Boyer 2013-12-24 14:19:19 UTC

That is a debug option that incurs additional overhead and a performance hit.  It also enables SCHEDSTATS which we currently have disabled because of bug 1013225.

*** This bug has been marked as a duplicate of bug 1013225 ***