AiSIO: Orchestrating Storage I/O Across CPUs and Accelerators

Despite providing massive parallelism and high-bandwidth local memory, modern accelerators typically access storage through CPU-centered I/O paths. As data-intensive workloads increasingly demand high-rate access to small and irregular I/O, these paths become a bottleneck, leading to underutilization of both compute and storage resources.
Accelerator-integrated Storage I/O (AiSIO) describes a class of system-software architectures that integrate accelerators such as GPUs into the storage I/O path while preserving operating-system managed storage abstractions and semantics, including files and file systems. In contrast, conventional storage access relies on CPU-initiated I/O with host-resident payloads, in which data is transferred through host memory before being consumed by accelerators. AiSIO instead encompasses two accelerator-integrated I/O modes: CPU-initiated I/O with device-resident payloads, where the host retains I/O initiation while directing data transfers directly into accelerator memory via peer-to-peer mechanisms, and device-initiated I/O with device-resident payloads, where accelerators themselves construct and submit storage operations using device memory for I/O payloads.
To make these paths interoperable with existing systems, AiSIO relies on host-coordinated control-plane services for device management, metadata handling, and policy enforcement, while allowing data movement and I/O execution to proceed along accelerator-optimized paths. This separation enables accelerators to participate directly in storage access without relinquishing operating-system control or file-system semantics.
This presentation introduces an open-source AiSIO system software implementation and experimental results comparing AiSIO paths to conventional CPU-initiated I/O with host-resident payloads, as well as contrasting CPU-initiated and device-initiated AiSIO modes. The evaluation quantifies the performance impact of integrating accelerators into the storage I/O path under a common Linux storage environment. Ongoing work focuses on upstreaming required operating-system primitives to the Linux kernel and libraries to support broader adoption.