vNV-Heap: An Ownership-Based Virtually Non-Volatile Heap for Embedded Systems

TL;DR

vNV-Heap is a novel ownership-based non-volatile heap designed for intermittently powered embedded systems, enabling energy-efficient, power-failure resilient object persistence with static operation bounds.

Contribution

It introduces the first ownership-based virtually non-volatile heap for embedded systems, providing static guarantees and energy efficiency for power-failure resilience.

Findings

More energy-efficient than existing approaches.

Provides static worst-case energy bounds.

Demonstrated on ESP32-C3 hardware.

Abstract

The Internet of Batteryless Things might revolutionize our understanding of connected devices by harvesting required operational energy from the environment. These systems come with the system-software challenge that the intermittently powered IoT devices have to checkpoint their state in non-volatile memory to later resume with this state when sufficient energy is available. The scarce energy resources demand that only modified data is persisted before a power failure, which requires precise modification tracking. We present vNV-Heap, the first ownership-based virtually Non-Volatile Heap for intermittently powered systems with guaranteed power-failure resilience. The heap exploits ownership systems, a zero-cost (i.e., compile-time) abstraction for example implemented by Rust, to track modifications and virtualize object persistence. To achieve power-failure resilience, our heap is designed and implemented to guarantee bounded operations by static program code analysis: For example, the heap allows for determining a worst-case energy consumption for the operation of persisting modified and currently volatile objects. The evaluation of our open-source implementation on an embedded hardware platform (i.e., ESP32-C3) shows that using our heap abstraction is more energy efficient than existing approaches while also providing runtime guarantees by static worst-case bounds.