Default Cpu speed how to write service not affecting cpu speed???

As a program runs... It pushes the cpu consumption increases the speed and consums more battery...
As a service runs virtiualy always it will push up the battery consumption.....

I would like to monitor wifi activity... Trigered by the external events but accept slow execution time if cpu state is low. uSec or mSec execution time i do not care... By preference independend of android cpu - battery saving setting....

How can i achieve that???

Sent from my GT-S5660 using XDA
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In need of a flexible workable phone (Gio)