Hibernation Mode for Computing Devices
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Solution Overview
Problem
Existing power-saving techniques in computing devices, such as sleep mode, are inadequate as they require maintaining power to volatile memory, leading to reduced battery life due to increased power consumption with larger RAM and smaller batteries in portable systems.
Innovation Solution
A hibernation mode is introduced where the active state of the computing device is preserved in non-volatile storage while power to volatile storage is turned off, allowing for the creation and restoration of a hibernation image using reanimation code, decompression, and decryption, with processes optimized for performance and security checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power is maintained to volatile memory during sleep mode to preserve active state, then wake-up speed is improved, but power consumption increases
Solution Approach 1:
The patent extracts the active state data from volatile memory and stores it in non-volatile memory, separating the data preservation function from the power-consuming volatile memory. This allows power to be completely cut off while preserving the ability to restore the active state.
Solution Approach 2:
The system performs preliminary action by saving the active state to non-volatile memory before entering hibernation mode. This pre-saved state enables rapid restoration without requiring continuous power to volatile memory, resolving the contradiction between wake-up speed and power consumption.
2Quantity of substance
If RAM capacity is increased to handle larger workloads, then processing capability is improved, but power consumption during sleep mode increases
Solution Approach 1:
The patent extracts the state data that would otherwise require large amounts of volatile memory and stores it in non-volatile memory. This eliminates the need to maintain power to large RAM capacities during sleep mode while preserving the ability to restore full system state.
Solution Approach 2:
The system uses non-volatile memory as a disposable storage medium for hibernation images. Instead of maintaining expensive, power-consuming volatile memory, the system periodically saves state to durable non-volatile storage, accepting that the state must be restored from scratch after each hibernation cycle.
3Volume of stationary object
If hibernation image is compressed to save storage space, then storage efficiency is improved, but decompression time increases
Solution Approach 1:
The system performs compression in advance when creating the hibernation image, reducing the storage requirements. The compression is done beforehand rather than in real-time during wake-up, eliminating the decompression time penalty from the critical wake-up path.
Solution Approach 2:
The patent uses hardware acceleration for decompression operations, moving the decompression function from software to hardware. This parallel processing approach dramatically reduces decompression time while maintaining high compression ratios, resolving the contradiction between storage efficiency and decompression speed.
4Reliability
If hibernation image is encrypted to secure data, then security is improved, but restoration speed decreases
Solution Approach 1:
The system performs encryption in advance when creating the hibernation image, securing the data at rest. The encrypted image is stored in non-volatile memory, and decryption is performed only when needed during restoration, maintaining security while minimizing impact on restoration speed.
Solution Approach 2:
The patent uses hardware acceleration for decryption operations, moving the decryption function from software to hardware. This parallel processing approach dramatically reduces decryption time while maintaining strong security encryption, resolving the contradiction between security and restoration speed.
Data Source
AI summary
One embodiment of the present invention provides a system that enables a computing device to save additional power by entering a “hibernation mode,” wherein the active state of the computing device is preserved in non-volatile storage while power to volatile storage is turned off. During operation, the system reanimates a computing device from a hibernation image by restoring reanimation code from the hibernation image and then executing the reanimation code. While executing this reanimation code, the system restores the rest of the hibernation image by, reading compressed data containing the rest of the hibernation image, and decompressing the compressed data using computational circuitry within the computing device. During this process, the decompression operations are overlapped with the reading operations to improve performance.