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

[Matt Ingenthron]

Aubrey Li wrote:
> On Sun, Apr 26, 2009 at 9:44 PM, Mark Haywood <Mark.Haywood at sun.com> wrote:
>   
>>> Should've been more specific in my reply, so:
>>>
>>> % vi /etc/power.conf  # Change to poll-mode
>>> % pfexec pmconfig
>>>
>>> % pfexec powertop # shows proc. always at max speed % pfexec reboot #
>>> After the reboot, powertop shows proc. at lower freq.
>>>
>>>       
>> It is either a bug or your system isn't idle enough for poll-mode to lower
>> the freq. either. I have successfully switched event-mode and poll-mode many
>> times without a reboot.
>>
>>     
>
> I checked it just now on my system(OpenSolaris200906-snv111),
> it works properly. When change to poll-mode, you'd better to set the
> "cpu-threshold" to "1s". The default scanning cycle is 15s, which means
> you need to wait for a while(>15s) to see the frequency transition.
> ============================
> cpupm                   enable poll-mode
> cpu-threshold           1s
> ============================
> After issue "pmconfig", you should see the lowest frequency residency
> in powertop if
> your system is idle.
>   

Some observations after some experimentation on my systems.  All were 
done with the system effectively 'idle'.  X was up with a GNOME session, 
and compiz was on, but most other apps that I usually run were down.  I 
was using gnome-terminal.

If I switch to event-mode, powertop does occasionally, for a refresh, 
show the pstate changing from something other than the highest 
frequency.  Observing it for a minute or so shows that it only happens 
maybe 10-20% of the time.  via mpstat 5, both cores show a median of 
about 97% idle (just eyeball observations)

In poll-mode with cpu-threshold set to 3s, I see the pstate changing 
much more frequently.  I also see pstates other than just the highest 
frequency and the lowest frequency. 

Like others have observed, powertop only ever shows me the 100% in any 
one pstate.  I believe that's where someone mentioned a bug. 

So I guess my question is, how should I get data to know if my usage 
pattern/system is best in event-mode or poll-mode?

Thanks in advance,

- Matt