Nonvolatile Memory Subsystem Power Management
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Solution Overview
Problem
Conventional mobile devices face inefficiencies in power consumption due to always-powered circuitry and inadequate task execution on general-purpose processors, leading to wasted energy and performance issues.
Innovation Solution
Implementing multi-processor subsystems with nonvolatile memory to store state data, allowing them to appear powered on while actually being off, and using compression/decompression techniques to quickly restore state data when needed, along with power control circuits to manage power states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all circuitry is always powered on to ensure services are available, then service availability is improved, but power consumption increases
Solution Approach 1:
The system is divided into multiple independent processor subsystems (first processor subsystem, second processor subsystem) that can be independently powered on or off. Each subsystem has its own volatile and nonvolatile memory, allowing selective activation based on task requirements while maintaining overall system availability.
Solution Approach 2:
State data representing the operational context of processor subsystems is pre-compressed and stored in nonvolatile memory before the subsystems are powered down. This preliminary action enables rapid restoration of the subsystem state without requiring full system power-on, thus maintaining service availability while reducing power consumption.
2Use of energy by moving object
If processor subsystems are turned off to save power, then power consumption is reduced, but system context restoration time increases
Solution Approach 1:
The essential system context (state data) is extracted from the processor subsystems and stored separately in nonvolatile memory in compressed form. This extraction allows the subsystems to be completely powered off while preserving their operational state, eliminating the time penalty of full system boot-up while enabling rapid restoration by only loading the compressed state data when needed.
Solution Approach 2:
The state data is compressed to reduce its size before storage in nonvolatile memory. This parameter change (reducing data size) directly reduces the time required to transfer and restore the state data from nonvolatile memory to volatile memory, thereby reducing power-up time while maintaining the ability to fully power down subsystems for power savings.
3Speed
If state data is stored in volatile memory for quick access, then access speed is improved, but data loss occurs during power failure
Solution Approach 1:
Nonvolatile memory serves as an intermediary between volatile memory and permanent storage. The compressed state data is stored in nonvolatile memory when the subsystem is powered down, preserving the data without requiring continuous power. When the subsystem needs to restart, the data is quickly transferred from nonvolatile memory to volatile memory, maintaining both data retention and fast access capabilities.
Data Source
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AI summary
Apparatuses and methods may include receiving a power-down command at a first subsystem comprising a first processor, a first volatile memory, a first nonvolatile memory, a first compressor/decompressor, and a first power control circuit, the first volatile memory being configured to store state data relating to operating conditions of the first subsystem. In response to receipt of the power-down command, the apparatuses and methods may cause the first compressor/decompressor to compress the state data to generate compressed state data and to cause the compressed state data to be stored in the first nonvolatile memory. In response to storage of the compressed state data in the first nonvolatile memory, the apparatuses and methods may cause the first power control circuit to power down the first subsystem.