Data-centric applications perform tasks that require intensive data processing and ample memory resources. These tasks have varying I/O access patterns, significantly impacted by the OS cache. Therefore, it is desirable to enable application-specific cache management without compromising memory efficiency. However, infusing user-level policies into the OS cache management is challenging because it is difficult to communicate application-level I/O semantics and access patterns to general-purpose OSs. This article addresses the challenge by enabling applications to safely convey their I/O semantics to OSs via eBPF, allowing for more application-specific control over the OS cache. To this end, we introduce P2Cache , a programmable OS page cache. P2Cache extends the Linux page cache with three new probe points (i.e., eviction , prefetching , and swapping ) that can support application-directed custom policies on OS cache management using eBPF programs. Our experimental results showed that P2Cache significantly enhanced the performance of an LLM inference, a graph processing application, and a database by up to 230%, 49%, and 18%, respectively, with minimal effort.

When multiple apps with different I/O priorities share a high-performance SSD, it is important to differentiate the I/O QoS level based on the I/O priority of each app. In this paper, we study how a modern flash-based SSD should be designed to support priority-aware read performance differentiation. From an in-depth evaluation study using 3D TLC SSDs, we observed that existing FTLs have several weaknesses that need to be improved for better read performance differentiation. In order to overcome the existing FTL weaknesses, we propose ReadGuard , a novel priority-aware SSD management technique that enables an FTL to manage its blocks in a fully read-latency-aware fashion. ReadGuard leverages a new read-latency-centric block quality marker that can accurately distinguish the read latency of a block and ensures that higher-quality blocks are used for higher-priority apps. ReadGuard extends an existing suspend/resume technique to handle collisions among reads. Our experimental results show that a ReadGuard -enabled SSD is effective in supporting differentiated read performance in modern 3D flash SSDs.

We propose P2Cache, an application-directed kernel-level page cache that allows an application developer to build a custom kernel-level page cache that matches the I/O characteristics of a target application. P2Cache extends a Linux kernel page cache by adding new probe points that are used to support application-programmable kernel page caches by eBPF programs. Our experimental results show that custom page caches implemented with our P2Cache achieve up to 32% performance improvement in data-intensive graph applications with little effort.

We propose a novel whitelist-based anti-ransomware solution called alohomora. Alohomora is based on our observation that an I/O activity of an application can be an effective abstraction level for managing I/O whitelisting. In alohomora, when a write request is sent to an SSD, its program context value (which is supported by a host CPU register) is passed to the SSD. The SSD checks if the request was pre-approved using the program context value, thus preventing ransomware from modifying files in the SSD. Our experimental results using a prototype alohomora system show that alohomora can achieve a strong security level against sophisticated ransomware attacks without degrading I/O performance.