Memory devices can be used as storage systems to provide a lower latency that can be achieved by disk and flash storage. However, traditional buffered input/output (I/O) and direct I/O are not optimized for memory-based storages. Traditional buffered I/O includes a redundant memory copy with a disk cache. Traditional direct I/O does not support byte addressing. Memory-mapped direct I/O, which optimizes file operations for byte-addressable persistent memory and appears to the CPU as a main memory. However, it has an interface that is not always compatible with existing applications. In addition, it cannot be used for peripheral memory devices (e.g., networked memory devices and hardware RAM drives) that are not interfaced with the memory bus. This paper presents a new Linux I/O layer, byte direct I/O (BDIO), that can process byte-addressable direct I/O using the standard application programming interface. It requires no modification of existing application programs and can be used not only for the memory but also for the peripheral memory devices that are not addressable by a memory management unit. The proposed BDIO layer allows file systems and device drivers to easily support BDIO. The new I/O achieved 18% to 102% performance improvements in the evaluation experiments conducted with online transaction processing, file server, and desktop virtualization storage.

内存设备可用作存储系统，以提供可以通过磁盘和闪存实现的较低延迟。但是，传统的缓冲输入/输出（I / O）和直接I / O并未针对基于内存的存储进行优化。传统的缓冲I / O包括带有磁盘缓存的冗余内存副本。传统的直接I / O不支持字节寻址。内存映射直接I / O，可优化可字节寻址的持久性内存的文件操作，并在CPU中作为主内存显示。但是，它的接口并不总是与现有应用程序兼容。另外，它不能用于未与存储总线接口的外围存储设备（例如，网络存储设备和硬件RAM驱动器）。本文介绍了一个新的Linux I / O层，即字节直接I / O（BDIO），可以使用标准的应用程序编程接口处理字节可寻址的直接I / O。它不需要修改现有的应用程序，并且不仅可以用于存储器，还可以用于存储器管理单元无法寻址的外围存储设备。提议的BDIO层允许文件系统和设备驱动程序轻松支持BDIO。在使用在线事务处理，文件服务器和桌面虚拟化存储进行的评估实验中，新的I / O将性能提高了18％至102％。提议的BDIO层允许文件系统和设备驱动程序轻松支持BDIO。在使用在线事务处理，文件服务器和桌面虚拟化存储进行的评估实验中，新的I / O将性能提高了18％至102％。提议的BDIO层允许文件系统和设备驱动程序轻松支持BDIO。在使用在线事务处理，文件服务器和桌面虚拟化存储进行的评估实验中，新的I / O将性能提高了18％至102％。