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Bug 1349770

Summary: turn CONFIG_RCU_NOCB_CPU_ALL=y off
Product: Red Hat Enterprise Linux 7 Reporter: Marcel Kolaja <mkolaja>
Component: kernel-rtAssignee: Luis Claudio R. Goncalves <lgoncalv>
kernel-rt sub component: Other QA Contact: Jiri Kastner <jkastner>
Status: CLOSED CURRENTRELEASE Docs Contact:
Severity: high    
Priority: high CC: bhu, daolivei, jshortt, williams
Version: 7.3Keywords: ZStream
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
While investigating another issue, Steven Rostedt noticed that enabling all CPUs as RCU no call back by default, CONFIG_RCU_NOCB_CPU_ALL, was adding latencies at specific code paths. Once this configuration is turned on at build time, impossible to turn this feature off. As this feature is very interesting to a certain niche of users, while indifferent for the others, we decided to disable the feature at build time. Users that may benefit from this feature can enable it at boot time using the rcu_nobcs= parameter.
 Story Points: ---
Clone Of: 1344077 Environment:
Last Closed: 2017-02-03 20:44:55 UTC Type: ---
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: 1344077    
Bug Blocks:    

Description Marcel Kolaja 2016-06-24 08:13:02 UTC 
This bug has been copied from bug #1344077 and has been proposed
to be backported to 7.2 z-stream (EUS).