Summary

This chapter was the second chapter in our exploration of the block layer in the kernel. The two main topics we discussed in detail were the multi-queue and device mapper frameworks. At the start of this chapter, we looked into the legacy single-request queue model in the block layer, its limitations, and its adverse impact on performance when working with modern storage drives and multi-core systems. From there, we introduced the multi-queue framework in the kernel. We described how the multi-queue framework addresses the limitations of the single-request model and improves the performance of modern storage drives, which are capable of supporting multiple hardware queues.

We also got a chance to look at the device mapper framework in the kernel. The device mapper framework is an essential part of the kernel and is responsible for implementing several technologies, such as multipathing, logical volumes, encryption, and raid. The most well known of these is logical volume...