Power management can be either centralized, distributed, or a combination of both. The type of devices supported by a power manager chip, or integrated into a system-on-chip presents different power management alternatives.
If the devices, such as memory chips, are homogenous; then a centralized power manager function becomes more attractive for a number of reasons:
(1) Same type memory chips have identical power-state values.
(2) Power-states, such as Active, Standby, Sleep, etc. are same.
(3) Minimal current state information needed per device to manage.
(4) Power manager functionality can be close to devices.
If the devices are non-homogeneous, then a distributed or centralized/distributed scheme makes more sense for a number of reasons:
(1) Non-homogeneous devices have different power-state values, requiring more distinct information per device.
(2) Power-states are not identical, such as a Processor chip, combined with memory chips.
(3) Centralized power management functions may be farther from devices being controlled.
If devices being controlled are farther from a centralized power management function, then latency of response may be a factor? This situation suggests a centralized/distributed structure may provide a better solution for best performance? Distributed power management functions might contain the same type of devices, for example. This simplifies power management for identical devices, as described above. Another possibility is only distributed power management, no centralized control. Centralized/distributed power management provides an opportunity to control lower level devices where local distributed-power management functionality may lack sufficient information.
The VisualSim Power_Manager supports distributed, or centralized, power management scenarios, whereas centralized/distributed structures might require RegEx execution of changing power-state, power-values to put certain devices into standby, sleep, or deep-sleep states based on higher level system information or activity. VisualSim contains expressions that can alter Power_Manager current state, power level, t_OnOff directly. In this manner, temperature, timing, or voltage levels can be incorporated to modify a device’s operational characteristics; i.e. a centralized Power_Manager Table can be dynamic.