Linux Storage System Analysis for e.MMC with Command Queuing

This white paper presents an analysis of the Linux storage system specifically focusing on e.MMC with command queuing. It outlines how Linux manages I/O requests from user space and discusses the performance limitations within the e.MMC subsystem. The document details the flow of storage I/O requests, highlighting the processes involved from the virtual file system (VFS) to the block layer and the subsequent handling by the block host interface driver. It explains the command queuing feature introduced in the e.MMC standard v5.1, which enhances command execution efficiency and random access performance. The paper includes a performance evaluation using the Ftrace tool to measure the impact of various system layers on I/O request latency. It provides data from two platforms, the Xilinx Zynq Zed Board and the NVIDIA Jetson TX1 Board, comparing their specifications and performance metrics. The findings aim to inform improvements in storage system design and optimization.