Autonomous vehicles (AVs) require consistently low-latency computations; however, operating system (OS) CPU scheduler can lead to high tail latency that threatens timely decision-making and safety. General-purpose OS schedulers prioritize fairness and throughput over individual task deadlines, posing challenges for complex AV workloads with mixed-criticality tasks. Despite extensive research on CPU scheduling, reinforcement learning (RL) has not been explored at the OS level due to feasibility concerns. This paper presents SCHED, the first RL-based CPU scheduling framework optimized for OS integration. SCHED learns a scheduling policy via reinforcement learning and deploys it as a lightweight, decision-tree-based scheduler. We demonstrate that SCHED remains sufficiently fast for OS-level integration compared to existing OS schedulers. Furthermore, we validate SCHED on a realistic autonomous vehicle pipeline, demonstrating its practical potential in maintaining low latency and ensuring safer, more responsive AV operations.

Self-Organizing Maps (SOM) promise a lightweight approach for multivariate time series anomaly detection in lightweight autonomous embedded systems. However, the enormous volume of time series data from autonomous systems testing requires huge SOMs with impractical search overhead. We present KDTree-SOM that effectively optimizes the winner node search for huge SOMs by reconstructing the SOM as a k-dimensional tree (kd-tree). KDTree-SOM achieves on average a 4 × inference time reduction for huge SOMs while achieving up to 95% anomaly detection accuracy with only KB-level memory overhead, demonstrating its potential for anomaly detection in lightweight autonomous embedded platforms.

We present ZoneTrace , a runtime monitoring tool for the Flash-friendly File System (F2FS) on Zoned Namespace (ZNS) Solid-state Drives (SSDs). ZNS SSD organizes its storage into zones of sequential write access. Due to ZNS SSD’s sequential write nature, F2FS is a log-structured file system that has recently been adopted to support ZNS SSDs. To present the space management with the zone concept between F2FS and the underlying ZNS SSD, we developed ZoneTrace , a tool that enables users to visualize and analyze the space management of F2FS on ZNS SSDs. ZoneTrace utilizes the extended Berkeley Packet Filter (eBPF) to trace the updated segment bitmap in F2FS and visualize each zone space usage accordingly. Furthermore, ZoneTrace is able to analyze on file fragmentation in F2FS and provides users with informative fragmentation histogram to serve as an indicator of file fragmentation. Using ZoneTrace ’s visualization, we are able to identify the current F2FS space management scheme’s inability to fully optimize space for streaming data recording in autonomous systems, which leads to serious file fragmentation on ZNS SSDs. Our evaluations show that ZoneTrace is lightweight and assists users in getting useful insights for effortless monitoring on F2FS with ZNS SSD with both synthetic and realistic workloads. We believe ZoneTrace can help users analyze F2FS with ease and open up space management research topics with F2FS on ZNS SSDs.

This paper summarizes the talks of a special session on the IPF 2.0 project, a collaborative German-US research project that leverages self-awareness principles for the self-management of distributed systems of autonomous multiprocessor systems-on-chip (MPSoCs).

The sequential write nature of ZNS SSDs makes them very well-suited for log-structured file systems. The Flash-Friendly File System (F2FS), is one such log-structured file system and has recently gained support for use with ZNS SSDs. The large F2FS over-provisioning space for ZNS SSDs greatly reduces the garbage collection (GC) overhead in the log-structured file systems. Motivated by this observation, we explore the trade-off between disk utilization and over-provisioning space, which affects the garbage collection process, as well as the user application performance. To address the performance degradation in write-intensive workloads caused by GC overhead, we propose a modified free segment-finding policy and a Parallel Garbage Collection (P-GC) scheme for F2FS that efficiently reduces GC overhead. Our evaluation results demonstrate that our P-GC scheme can achieve up to 42% performance enhancement with various workloads.

Linux prevents errors due to physical memory limits by swapping out active application memory from main memory to secondary storage. Swapping degrades application performance due to swap-in/out latency overhead. To mitigate the swapping overhead in periodic applications, we present ProSwap: a period-aware proactive and adaptive swapping policy for em-bedded systems. ProSwap exploits application periodic behavior to proactively swap-out rarely-used physical memory pages, creating more space for active processes. A flexible memory reclamation time-window enables adaptation to memory limitations that vary between applications. We demonstrate ProSwap's efficacy for an autonomous vehicle application scenario executing multi-application pipelines, and show that our policy achieves up to 1.26×performance gain via proactive swapping.

The efficiency of secure deletion is highly dependent on the data layout of underlying storage devices. In particular, owing to the sequential-write constraint of the emerging Shingled Magnetic Recording (SMR) technology, an improper data layout could lead to serious write amplification and hinder the performance of secure deletion. The performance degradation of secure deletion on SMR drives is further aggravated with the need to securely erase the file system metadata of deleted files due to the small-size nature of file system metadata. Such an observation motivates us to propose a secure-deletion and SMR-aware space allocation (SSSA) strategy to facilitate the process of securely erasing both the deleted files and their metadata simultaneously. The proposed strategy is integrated within the widely-used extended file system 4 (ext4) and is evaluated through a series of experiments to demonstrate the effectiveness of the proposed strategy. The evaluation results show that the proposed strategy can reduce the secure deletion latency by 91.3% on average when compared with naive SMR-based ext4 file system.

Modern nonvolatile memories (NVMs) are widely recognized as energy-efficient replacements of classical memory/storage media, such as SRAM, DRAM, and mechanical hard disk. Among the popular NVMs, the skyrmion racetrack memory (SK-RM) is well known for its high storage density and unique supports of insert/delete operations. However, the existing algorithms designed for classical media might experience serious performance degradation when working on the SK-RM, due to the distinct characteristics of SK-RM. Thus, the existing algorithms should be redesigned to adapt to the brand-new memory model based on the SK-RM, so as to fully reveal the potentials of SK-RM. In particular, many existing algorithms tend to access the in-memory data in a random-hopping fashion, which generates many time-consuming shift operations of SK-RM. It is therefore crucial for the existing algorithms to eliminate unnecessary shift operations of SK-RM to boost the performance of the algorithms. In many modern applications, such as multimedia and data analysis, it is a common operation to process two or more arrays/vectors of data to perform certain computation tasks. In the arrays/vectors, an appropriate data placement strategy is critical for avoiding unnecessary shift operations of SK-RM. The observation thus motivates this work in proposing a recursive back-to-back data placement manner to effectively reduces the shift operations of SK-RM. To demonstrate the back-to-back data placement, we take sorting algorithms as a case study, and propose a novel shift-limited sorting algorithm for SK-RM. Analytical studies show that the shift-limited sort effectively enhances the time complexity of classical merge sort from O(dn lg n) to O(n lg n), where d is the bit distance between adjacent access ports on the nanotracks of the SK-RM. After that, the efficacy of the proposed shift-limited sort is then verified by experimental studies, where the results are encouraging.