TCP/IP Illustrated

Chapter 2. Mbufs: Memory Buffers

2.1. Introduction

Networking protocols place many demands on the memory management facilities of the kernel. These demands include easily manipulating buffers of varying sizes, prepending and appending data to the buffers as the lower layers encapsulate data from higher layers, removing data from buffers (as headers are removed as data packets are passed up the protocol stack), and minimizing the amount of data copied for all these operations. The performance of the networking protocols is directly related to the memory management scheme used within the kernel.

In Chapter 1 we introduced the memory buffer used throughout the Net/3 kernel: the mbuf, which is an abbreviation for “memory buffer.” ...