Whitepaper: Understanding Write Combining on Arm

Author: Pavel Shamis, Principal Research Engineer

Write CombiningWrite Combining (WC) is a specialized memory type defined by the x86-64 architecture that is used for gathering multiple stores into burst transactions over the system bus. WC is commonly used on x86-64 platforms for interaction with I/O and other peripheral devices.

In this whitepaper we provide an overview of the Arm architecture memory types that provide WC-like capabilities. In addition, the whitepaper provides advice for Arm system implementers on providing compatibility with existing hardware leveraging WC capabilities for performance optimizations.

This whitepaper is intended for Arm SoC and system components designers and system software developers.