NUMA

2 articles

Tech 22 Sep 2026 7 min read

NUMA First-Touch Placement Ties Physical Pages to the Faulting CPU

On a NUMA machine, reserving virtual address space does not necessarily choose the physical NUMA node that will supply every page. For anonymous memory, physical allocation commonly happens later, when a CPU first faults on a page. Under the default local allocation policy, that fault can make initialization order part of the memory-placement decision. This behavior is often called first-touch placement. The thread that first writes or otherwise faults a page can cause Linux to allocate backing memory near the NUMA node on which that thread is running, subject to the active memory policy, cpuset constraints, available memory, and kernel fallback behavior.

Linux NUMA

Tech 17 Sep 2026 6 min read

NUMA Makes Memory Location Part of Access Cost

NUMA Makes Memory Location Part of Access Cost A large multiprocessor server can expose one physical address space while giving different processors different paths to that memory. A load from a page attached to the processor running a thread can take a shorter route than a load from memory attached to another processor package or NUMA node. This arrangement is called non-uniform memory access, or NUMA. It lets systems scale memory capacity and bandwidth across multiple processor sockets or chiplet groups without forcing every memory request through one centralized controller.

CPU Memory