Bugs item #1353119, was opened at 2005-11-10 13:35
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Bernd Paysan (paysan)
Assigned to: Nobody/Anonymous (nobody)
Summary: cpufreq unreliable with Athlon64 X2 (dual core)

Initial Comment:
Hi,  
  
As far as I can tell, cpufreq/powersaved (of 0.10.15.1, as in 
SuSE 10.0) seems to have a  severe problem with the 
Athlon64 X2 dual core chips. If I load just one core, the 
CPU frequency boost is unreliable (toggles  between 1GHz 
and 2GHz). Loading the second core, too, sort-of-fixes that 
problem.  
 
The reason is obvious: The Athlon X2 has a *single* CPU  
frequency setting which affects *both* cores. So you can't  
simply use a SMP setting, treating the two CPUs as two  
processors with two speed settings, you have to know that  
it's a dual-core CPU, and that you can't independently set  
the CPU frequency. If one core is loaded, both must run at  
double frequency.  
  
Note that the kernel does know about this fact:  
  
/sys/devices/system/cpu/cpu0/cpufreq> cat affected_cpus   
0 1  
/sys/devices/system/cpu/cpu1/cpufreq> cat affected_cpus   
0 1  
  
Setting powersaved to be more verbose confirms the  
confusion (the following is with one core loaded by an  
endless loop, the other core loaded lightly):  
  
-------------------------------------------------  
Nov 10 13:24:48 linux [powersave]: Info (setSpeed:90)  
Speed set to: 1800000KHz  in  
file /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed  
Nov 10 13:24:48 linux [powersave]: Info (setSpeed:90)  
Speed set to: 2000000KHz  in  
file /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed  
Nov 10 13:24:48 linux [powersave]: Info (adjustSpeed:196)  
Speed directly set to max (2000000) MHz  
Nov 10 13:24:48 linux [powersave]: Info  
(decreaseSpeed:138) current speed: 2000000KHz     new  
speed: 1800000KHz  
Nov 10 13:24:48 linux [powersave]: Info (setSpeed:90)  
Speed set to: 1800000KHz  in  
file /sys/devices/system/cpu/cpu1/cpufreq/scaling_setspeed  
Nov 10 13:24:48 linux [powersave]: Info (adjustSpeed:207)  
Speed decreased to (1800000) MHz  
Nov 10 13:24:48 linux [powersave]: Info  
(decreaseSpeed:138) current speed: 2000000KHz     new  
speed: 1800000KHz  
Nov 10 13:24:48 linux [powersave]: Info (setSpeed:90)  
Speed set to: 1800000KHz  in  
file /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed  
Nov 10 13:24:48 linux [powersave]: Info (adjustSpeed:207)  
Speed decreased to (1800000) MHz  
Nov 10 13:24:48 linux [powersave]: Info (setSpeed:90)  
Speed set to: 2000000KHz  in  
file /sys/devices/system/cpu/cpu1/cpufreq/scaling_setspeed  
Nov 10 13:24:48 linux [powersave]: Info (adjustSpeed:196)  
Speed directly set to max (2000000) MHz  
Nov 10 13:24:48 linux [powersave]: Info  
(decreaseSpeed:138) current speed: 1800000KHz     new  
speed: 1000000KHz  
Nov 10 13:24:48 linux [powersave]: Info (setSpeed:90)  
Speed set to: 1000000KHz  in  
file /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed  
Nov 10 13:24:48 linux [powersave]: Info (adjustSpeed:207)  
Speed decreased to (1000000) MHz  
-------------------------------------------------  
  
This seems to be a pretty severe bug, rendering  
powersaved pretty unusable on a dual-core Athlon64.  

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=700009&aid=1353119&group_id=124576
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