一句话：提出 xUI 处理器扩展，用硬件安全点与中断转发等机制，实现兼具轮询性能与异步通知效率的用户级中断。
用户级中断（如 Intel UIPI）旨在让应用直接接收硬件通知而不陷入内核，但其时序行为不透明、灵活性不足，实践中往往仍需退化为共享内存轮询。本文通过分析与测量解构 Intel 现有 UIPI 设计，建立其精确的时序模型，并据此提出四项增强：tracked interrupts、hardware safepoints、kernel bypass timer 与 interrupt forwarding，合称 xUI。作者在 gem5 中对 xUI 建模，并在三个用例上评估：高性能用户级运行时的抢占、基于 DPDK 的 L3 路由器 IO 通知，以及仿照 Intel Data Streaming Accelerator 的流式加速器合成负载。结果表明，xUI 能同时提供共享内存轮询级别的性能与异步通知的能效。
Extended user interrupts (xUI) is a set of processor extensions that builds on Intel's UIPI model of user interrupts, for enhanced performance and flexibility. This paper deconstructs Intel's current UIPI design through analysis and measurement, and uses this to develop an accurate model of its timing. It then introduces four novel enhancements to user interrupts: tracked interrupts, hardware safepoints, a kernel bypass timer, and interrupt forwarding. xUI is modeled in gem5 simulation and evaluated on three use cases -- preemption in a high-performance user-level runtime, IO notification in a layer3 router using DPDK, and IO notification in a synthetic workload with a streaming accelerator modeled after Intel's Data Streaming Accelerator. This work shows that xUI offers the performance of shared memory polling with the efficiency of asynchronous notification.
@inproceedings{AydogmusGZGTOT25,
title = {Extended User Interrupts (xUI): Fast and Flexible Notification without Polling},
author = {Berk Aydogmus and Linsong Guo and Danial Zuberi and Tal Garfinkel and Dean Tullsen and Amy Ousterhout and Kazem Taram},
booktitle = {ASPLOS},
year = {2025},
doi = {10.1145/3676641.3716028}
}