lowalloc

Lowalloc is a term used to describe memory management techniques that emphasize minimizing dynamic allocations during runtime by preallocating large memory pools and serving allocations from those pools. The approach trades some flexibility for speed, determinism, and cache efficiency, making it common in performance-critical or resource-constrained environments.

Core ideas include preallocated pools, arena or slab-like allocators, and per-thread caches. Allocations are typically small and of fixed or closely matching sizes, drawn from a pool rather than from a general-purpose allocator. Deallocation may return memory to the pool for quick reuse, or it may be coordinated with a higher-level garbage collector or reset mechanism, depending on the system design. This structure often yields fast allocation and deallocation paths and reduces memory fragmentation.

Common implementations and patterns related to lowalloc include slab allocators (fixed-size object pools suitable for many small objects), arena allocators (large contiguous regions with fast resets or releases), and object pools (reusing instances of expensive-to-allocate types). These approaches improve cache locality and can provide more predictable latency, which is beneficial for real-time, game, and high-concurrency applications.

Advantages of lowalloc include deterministic latency, improved cache performance, and reduced overhead from general-purpose allocators. Trade-offs encompass potential memory waste due to pool sizing, added complexity in allocator design, and the need to manage pool growth or shrinkage. In systems with long-lived, irregular allocations, lowalloc may be less suitable without auxiliary strategies.

See also: memory allocator, slab allocator, arena allocator, object pool.