To Do List
1. Initial Analysis
- Catalog processor power management features
- Analyze Linux power management policies
Results
Processor Features
- Intel Core 2 Duo
| C-state | Max Power Consumption | Description |
| C0 (busy wait) | 35 Watts (TDP) | normal |
| C1 | 13.5 Watts | either AutoHALT or MWAIT(C1); the latter gives you a way to wait on a memory location |
| C2 | 12.9 Watts | can use MWAIT(C1), will process snoops |
| C3 | 7.7 Watts | flush L1 into L2. monitors remain. all clocks are shutdown. |
| C4 | 1.2 Watts | identical to C3, but if both cores do it, the core goes into deeper sleep. |
| C6 | 0? | saves processor state to SRAM, voltage can go to zero |
C1: HALT instruction puts you into C1/AutoHALT. MWAIT(C1) overview: basically like AutoHALT, but you can wait on a memory region (set up with MONITOR) this way.
| Packate states | Description |
| Stop-grant | Entered if one core is in C2. Clock is running, and responds to interrupts. |
| Deep-sleep | |
| Deeper-sleep | |
| Deep power-down (C6) | both cores have entered C4 |
Ref:
- http://www.lesswatts.org/documentation/silicon-power-mgmnt/
- datasheet
- core 2 mobile datasheet
- http://software.intel.com/en-us/articles/cpu-power-utilization-on-intel-architectures/
- Core 2 architecture overview
- Intel Atom
- AMD Athlon (for notebooks?)
ADA5000IAA5CU: The envelope is 31-89 Watts for the DVFS states. Stop-grant brings you down to 3 watts, but it doesn't look like there's a lot between there. This is a "desktop" processor.
Ref: [http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/33954.pdf
