Cache is King: Smart Page Eviction with eBPF

2025-02-04

AI Summary

Traditional Linux page caching employs fixed replacement policies, which struggle to adapt to diverse application workloads; kernel-level policy customization remains impractical due to high development complexity and security risks. This paper introduces CacheBPF—the first eBPF-based programmable page cache framework—that safely injects user-defined eviction policies into the kernel via tracepoints, requiring no kernel source modification and supporting cross-process policy sharing with strict isolation. It pioneers the integration of eBPF into core OS memory management, leveraging a policy sandbox and application-aware metadata tagging to ensure both safety and flexibility. Evaluated under realistic workloads, CacheBPF achieves up to 70% higher throughput and 58% lower tail latency compared to baseline policies, demonstrating that fine-grained, workload-specific eviction strategies significantly improve performance for heterogeneous applications.

Technology Category

• Machine Learning: Hardware-aware ML
• Multiagent Systems: Mechanism Design
• Search and Optimization: Evolutionary Computation

Application Category

• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization

Abstract

The page cache is a central part of an OS. It reduces repeated accesses to storage by deciding which pages to retain in memory. As a result, the page cache has a significant impact on the performance of many applications. However, its one-size-fits-all eviction policy performs poorly in many workloads. While the systems community has experimented with a plethora of new and adaptive eviction policies in non-OS settings (e.g., key-value stores, CDNs), it is very difficult to implement such policies in the page cache, due to the complexity of modifying kernel code. To address these shortcomings, we design a novel eBPF-based framework for the Linux page cache, called $ exttt{cachebpf}$, that allows developers to customize the page cache without modifying the kernel. $ exttt{cachebpf}$ enables applications to customize the page cache policy for their specific needs, while also ensuring that different applications' policies do not interfere with each other and preserving the page cache's ability to share memory across different processes. We demonstrate the flexibility of $ exttt{cachebpf}$'s interface by using it to implement several eviction policies. Our evaluation shows that it is indeed beneficial for applications to customize the page cache to match their workloads' unique properties, and that they can achieve up to 70% higher throughput and 58% lower tail latency.

Problem

• Customizing page cache eviction policies
• Implementing eBPF-based framework without kernel modification
• Improving application performance through specific cache strategies

Innovation

• eBPF-based framework for Linux
• Customizable page cache policy
• Enhanced throughput and latency