NUMA and multi-socket

The one account tying first touch, policy scope, zone reclaim and page movement together from the implementer's side.

Defines nodes, zonelists and the distance-ordered fallback that places an allocation once local memory runs out.

The normative statement of policy scopes, every mode including weighted interleave, and the cpuset intersection rule.

Defines numa_hit, numa_miss and numa_foreign, the counters that show whether a policy put pages where it said.

Reference implementation of the policy API, prints the distance table and binds a binary that cannot be rebuilt.

Explains the firmware-rated latency and bandwidth per initiator and target, and memory-side caches, that rank nodes.

Where Intel names the mesh, UPI socket links, the directory-running home agent, and how SNC splits the cache.

Defines SNC on current parts as one node per compute die, and fixes the numactl and numastat checks of placement.

Discloses the I/O die, GMI and xGMI links, the NPS modes with their interleave widths, and the cache-as-NUMA override.

Defines the mesh, the home nodes holding the system cache and snoop filter, and the gateways joining sockets or CXL.

Defines per-page migration of a running process, and a query reporting each page's node, the direct test of first touch.

Defines the hinting-fault sampling behind automatic balancing and tiering, and warns the overhead may not pay off.

Proves against the kernel balancer that controller and link congestion, not remote latency, is what placement manages.

Measures the node-to-node latency and bandwidth matrix and loaded latency on the x86 at hand, which no datasheet states.

Tabulates measured bandwidth by NPS mode, cores per die, boost and SMT, so the NPS trade-off is shown, not asserted.