#11824 NORM 12.1.0: CONFIG_NO_HZ seems to interfere with idle time accounting

Zarro Boogs per Child bugtracker at laptop.org
Mon Apr 30 17:40:40 EDT 2012

#11824: CONFIG_NO_HZ seems to interfere with idle time accounting
 Reporter:  pgf     |                 Owner:                                   
     Type:  defect  |                Status:  new                              
 Priority:  normal  |             Milestone:  12.1.0                           
Component:  kernel  |               Version:  Development build as of this date
 Keywords:          |           Next_action:  never set                        
 Verified:  0       |   Deployment_affected:                                   
Blockedby:          |              Blocking:                                   
 on a (fairly) idle XO-1.75, run "top", and observe the %id field, which is
 an indication of cpu idleness.

 with not much happening on the laptop, the idle percentage will often dip
 to 60% or 50%.  these values (anything less than 85% idle) can keep the
 system from being suspended by powerd's idleness heuristic.

 adding nohz=off to the kernel cmdline, and re-running the test, shows more
 reasonable idles times in the 90% range.

 this seems to be an issue only on 1.75, so presumably is ARM-related.

Ticket URL: <http://dev.laptop.org/ticket/11824>
One Laptop Per Child <http://laptop.org/>
OLPC bug tracking system

More information about the Bugs mailing list