PowerTOP's FAQ
a never ending work in progress
- What's PowerTOP?
PowerTOP is an observability tool that allows you to analyze your CPU's power management features, how they are being utilized and what kinds of system activity are interfering with it. - How do I run it ?
Just type 'powertop' at a command line prompt. You need an OpenSolaris based system running build 100 or later. OpenSolaris 2008.05 and newer versions all include it. - Does it work on both x86 and SPARC platforms ?
PowerTOP runs on x86 and sun4v architectures. - What are C and P-states ?
Modern processors allow the operating system to place them in different levels of utilization in order to optimize the system's overall power performance. C-states are the different levels of idleness that a CPU can be placed in. An idle level is where the processor shuts down some of its components and ceases to execute, reducing the energy consumption. The deeper the state, the greater the portion of the processor that is shut down. C-states are numbered C0 through CN, 0 being an active processor and N the deepest possible idle level.
P-states are the different frequency levels at which a processor may execute. Similarly to what happens with C-states, the operating system is capable of transitioning the hardware from a frequency to another. This reduces the CPU's processing capacity while still being able to execute instructions.
The number of C and P-states supported depends on your systems' architecture, and tend to vary quite a bit.
on 2009/10/26 12:10