Explore the concept, implementation and management of KSM in the Linux 2.6.32 kernel

Introduction: As a system hypervisor, Linux® has several innovations. An interesting change in the 2.6.32 kernel is that KSM (KernelSamepageMerging) allows this system hypervisor to reduce concurrent virtual machines by merging memory pages. Number of. This article explores the concepts behind KSM (such as storage decoupling), the implementation of KSM, and how to manage KSM.

Server Virtualization

Virtualization technology began to appear in the 1960s and became popular through the IBM® System/360® minicomputer. Fifty years later, virtualization technology has developed by leaps and bounds, making it possible for multiple operating systems and applications to share a server. This particular use case (called server virtualization) is evolving into the data center, as a single machine can be used to host 10 (typically) or more virtual machines (VMs), as shown in Figure 1. These virtualizations make infrastructure more dynamic, more power-efficient, and (therefore) more economical.

Figure 1. Server consolidation via virtualization

The pages are all the same. This feature is useful if the operating system and application code as well as constant data are the same between VMs. When pages are unique, they can be merged, thus freeing up video memory for use by other applications. Figure 2 demonstrates video memory sharing and shows the usefulness of more available idle video memory when sharing pages between VMs with identical content.

Figure 2. Video memory sharing across VMs

Feature naming

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