The use of virtual memory practically eliminated the need for the contiguity of physical mem- ory allocation as physically discontiguous memory can be contiguous in the virtual address space. Unfortu- nately, avoiding performance degradation for memory- intensive workloads on modern CPUs requires a steady supply of contiguous physical memory, making external physical memory fragmentation in modern operating systems a serious issue once again.

This paper presents the design and implementation of several several anti-fragmentation mechanisms for the FreeBSD kernel. Parts of this work were sponsored by the Google Summer of Code ’23 program.