Memory Layout, Allocations, and Cache Locality

Rust memory optimization is the cornerstone of high-performance systems. Unlike garbage-collected languages where the runtime controls allocation, Rust gives you fine-grained control over where and when memory is allocated. This series teaches you how to exploit that control to build extremely fast programs.

Memory layout and cache locality determine whether your CPU cache hits or misses millions of times per second. A single cache miss can cost 200–300 CPU cycles, equivalent to thousands of nanoseconds. Struct field ordering, arena allocators, and data-oriented design let you keep hot data on the same cache line, transforming your inner loops from bottlenecks into blazing-fast cores.

This series progresses from foundational concepts (how Rust lays out structs in memory) through intermediate techniques (arena and bump allocators, heap allocation reduction) to advanced patterns (cache-aware loops, custom allocators, and profiling real workloads). By the end, you will understand how to profile memory usage, choose the right allocator for your hot path, and design data structures that work with your CPU's cache hierarchy instead of against it.

Articles in this series

• Understanding Rust Memory Layout: Bytes, Struct Fields, and Alignment
• Struct Field Ordering for Cache Efficiency: Why Order Matters
• Repr Attributes Demystified: Controlling Binary Layout in Rust
• Reducing Heap Allocations: Stack-First Patterns and RAII
• Arena Allocators Explained: Building Efficient Memory Pools
• Bump Allocators: Ultra-Fast Linear Allocators for Hot Paths
• Cache Locality and Data-Oriented Design: Layout for Speed
• Building Tight Loops: Optimizing Inner Loop Memory Access Patterns
• Profiling Memory Allocations: Tools and Techniques for Rust
• Custom Allocators in Rust: Tailoring Memory to Your Workload