Understanding the Linux Block Layer - From Single Queue to Multi-Queue Architecture

Explore the evolution and architecture of the Linux block layer in this 42-minute conference talk that traces the transformation from single-queue to multi-queue design. Discover how modern storage hardware like SSDs, NVMe devices, and high-throughput RAID systems exposed critical performance bottlenecks in the traditional single-queue block layer architecture. Learn about the modern multi-queue block layer (blk-mq) and understand how it addresses these performance challenges to meet the demands of contemporary storage technology. Follow a detailed walkthrough of what happens under the hood during a simple file copy operation using the cp command, tracing the complete data flow across multiple Linux subsystems including the VFS layer, page cache, I/O scheduler, block layer, and storage drivers. Gain comprehensive insights into Linux I/O processing and understand the fundamental role the block layer plays in moving data between user applications and storage devices.