[Discuss] PowerTop & Conky, how to combine?

[Arjan van de Ven]

Carlos R. Mafra wrote:
> BasaBuru wrote:
>> El Tuesday 06 November 2007 16:58:46 Arjan van de Ven escribió:
>>
>>> many desktop environments, including gnome, kde and xfce, have their
>>> own power meter / battery monitor tool.... I would expect that you
>>> already have one of these in your system..
>> I'm finding for one app what show the power usage, like powertop "Power usage 
>> (5 minute ACPI estimate) : 21.3 W (1.9 hours left)"
>>
>> I'm look for in Debian and Net........ i can't find one.
> 
> I had this problem also, and I didn't want to use kde or gnome. So I modified
> the wmlaptop app to show the power usage of my laptop (also CPU temperature, 
> CPU frequency, cpuload, battery % etc).
> 
> First I had to modify wmlaptop to use the ondemand cpu governor, and then I
> copied the relevant powertop source code regarding the power usage into
> wmlaptop.
> 
> You can check how wmlaptop looks with my modifications here:
> 
> While battery is charging the power usage is 'green':
> http://www.ift.unesp.br/users/crmafra/wmlaptop_ondemand1.png
> 
> The power usage is written in red when battery is discharging:
> http://www.ift.unesp.br/users/crmafra/wmlaptop_ondemand2.png
> 
> You can download this modified wmlaptop (version 1.5) there too.
> 
> Note that my modified wmlaptop generates a few wakeups, because
> it polls the cpu frequency and all that. 
> 
> I really would like to know if there is a kernel mechanism which  
> would notify some application whether the cpu frequency changed.
> I tried to use dnotify to check the scaling_cur_freq file in /sys,
> but that didn't work (and I think that doesn't make sense :-))

the problem is that the frequency can (and will) change thousands of 
times per second.. the overhead of notifying userspace for that is ... 
immense.