The overhead of the kernel storage path accounts for half of the access latency for new NVMe storage devices. We explore using BPF to reduce this overhead, by injecting user-defined functions deep in the kernel's I/O processing stack. When issuing a series of dependent I/O requests, this approach can increase IOPS by over 2.5$\times$ and cut latency by half, by bypassing kernel layers and avoiding user-kernel boundary crossings. However, we must avoid losing important properties when bypassing the file system and block layer such as the safety guarantees of the file system and translation between physical blocks addresses and file offsets. We sketch potential solutions to these problems, inspired by exokernel file systems from the late 90s, whose time, we believe, has finally come!

中文翻译：

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BPF的存储方式：基于exokernelnel的方法

内核存储路径的开销占新NVMe存储设备访问延迟的一半。我们探索通过在内核的I / O处理堆栈中注入用户定义的函数来降低BPF的开销。当发出一系列相关的I / O请求时，通过绕过内核层并避免用户内核边界交叉，此方法可以将IOPS增加2.5倍以上，并将延迟减少一半。但是，在绕过文件系统和块层时，我们必须避免丢失重要的属性，例如文件系统的安全保证以及物理块地址和文件偏移量之间的转换。我们从90年代末的exokernel文件系统中汲取灵感，为这些问题提供了可能的解决方案，我们相信，这些时代终于来临！