[indiana-discuss] b111a: Power Management and nwam-issue ?

[Brock Pytlik]

Mark Haywood wrote:
> Brock Pytlik wrote:
>> [snip]
>> Thanks, that made a huge difference. I'm now spending about 65-70% of 
>> time in C1 (down from 80%), but now I'm seeing my P-states change 
>> instead of being pegged at 2531Mhz. When I'm essentially idling, I'm 
>> @ 800Mhz, and popping up to higher P states periodically.
>
> That seems like a lot of time to be spending in C0. Is your system 
> supposed to be essentially idle? I see a lot of wakeups due to audiohd?
>
Yeah, I'm not sure why audiohd is firing that much. I was "idle" not 
idle. I had a few apps running, firefox, thunderbird, pidgin if I 
remember right, but nothing that was taxing the machine in any 
meaningful way. Whatever it was though apparently went away b/c I'm now 
at 88% in C1 and audiohd isn't showing up at all in that list. I'm not 
sure why it was in the first place.
>>
>>
>> One other thing I'm noticing that seems suspicious is that my 
>> percentage is always at 100% for one P state. It seems somewhat 
>> unlikely (to me at least) that it's changing P states exactly on 
>> every 5 second interval that powertop's using to sample. Is it 
>> possible that the percentage isn't doing quite what's expected?
>
> This doesn't surprise me all that much. In poll-mode the P-State 
> transitions are much less frequent. You probably won't see them change 
> often at all unless you either go from being idle to pretty busy or 
> from busy to idle. In event-mode you should see transitions many times 
> a second even on a somewhat idle system.
>
Well, I guess I expected that the percentage being reported was the 
percent of time (roughly) spent in that P-state during the last sampling 
interval (5 seconds). So, when I taxed the machine and made it jump from 
800Mhz to 2531Mhz, I was surprised that during that interval, the 
percentage was still 100%. For example if I started taxing the machine 
2.5 seconds after the last refresh, I would've expected 50% @ 800Mhz and 
50% @ 2531Mhz. Perhaps I'm just misunderstanding the meaning of the 
number I'm seeing, but that's what this sentence from the man page would 
lead me to believe:
 The tool analyzes system activity periodically and  displays a  
summary  of  how  long the processor is executing at each supported 
power state.

Thanks,
Brock
> Mark
>
>>
>> Brock