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Bug 1290 - kpowersave 100% CPU usage
Summary: kpowersave 100% CPU usage
Status: RESOLVED NOTOURPROBLEM
Alias: None
Product: TDE
Classification: Unclassified
Component: other (any) (show other bugs)
Version: 3.5.13 [Trinity]
Hardware: Other Linux
: P5 blocker
Assignee: Timothy Pearson
URL:
Depends on:
Blocks:
 
Reported: 2012-10-26 09:54 CDT by Sciurus vulgaris
Modified: 2013-03-28 20:01 CDT (History)
4 users (show)

See Also:
Compiler Version:
TDE Version String:
Application Version:
Application Name:

Attachments
Kpowersave burdensome processor (13.54 KB, text/plain)
2013-03-28 12:36 CDT, Slávek Banko 		Details
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Description Sciurus vulgaris 2012-10-26 09:54:03 CDT 
Sometimes kpowersave needs 100% CPU.

Tested on:
OS: Debian 6.0
Trinity Version: 3.5.13.1

OS: openSuSE 12.2
KDE Version: 3.5.10

Seems to occur when display blacks out(power down display, or activates screensaver?). Sometimes i just see the hourglass and the background image from TDM/KDM. After moving the mouse pointer the desktop appears again and kpowersave runs amok and burns down my battery.
Comment 1 Calvin Morrison 2012-12-02 22:31:29 CST 
This is confirmed, but is unlikely to be resolved. 

Basically HAL is no longer functioning correctly on newer distributions, so I don't see any resolution to kpowersave on our 3.5.13.1 release. R14 (next major release) offers a kpowersave without HAL option, which should resolve the problem. Nightlies are available for debian, with kpowersave available.
Comment 2 Slávek Banko 2013-03-28 12:36:52 CDT 
Created attachment 1127 [details]
Kpowersave burdensome processor

My colleague can cause this problem. I saved backtrace such a state.

It is interesting that with kernel 2.6.32 (from squeeze) it's okay, but with kernel 3.2.x (from squeeze-backports) on same hardware kpowersave consumes 100% cpu.
Comment 3 Timothy Pearson 2013-03-28 13:08:30 CDT 
Can you switch to kpowersave-nohal on TDE R14?  I intend to deprecate, if not entirely remove, the original kpowersave in R14 due to its dependence on HAL.

The backtrace posted indicates a problem somewhere within the DBUS communication routines; unless this same problem occurs with kpowersave-nohal, I don't see any reason to use scarce developer resources in an attempt to resolve it.

Tim
Comment 4 Slávek Banko 2013-03-28 20:01:48 CDT 
I hope that I have some other informations that might be helpful to someone else. On the laptop, on which I had a chance to thoroughly examine, the initial situation was this:

kernel 2.6.32 (squeeze) => adjusting the brightness in kpowersave is fully functional => no problems with suspend / resume

kernel 3.2.x (squeeze-backports) => adjusting the brightness in kpowersave is available, but it does not work => after resume the CPU is loaded to 100%

With kernel 3.2.x is in /sys/class/backlight two folders - acpi_video0 and intel_backlight. Manually setting values ​​to backlight files in both folders works, but not work adjusting backlight in kpowersave. Slider is available, but does not affect the backlight.

After adding acpi_backlight=vendor to the kernel command line, instead of acpi_video0 is in /sys/class/backlight folder dell_backlight. With this adjusting backlight in kpowersave works again and the problem with 100% CPU load is gone.