for_each_node_numadist(9)

💅 for_each_node_numadist(9) — the Kernel API Manual, but make it make sense

okay bestie, so this is a page from the Kernel API Manual (for_each_node_numadist(9)), and it's literally about walking NUMA nodes in order of how far away they are. no cap, it's giving "shortest road trip first" energy 🚗✨

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✨ NAME ✨

for_each_node_numadist — iterate over nodes in increasing distance order, starting from a given node 🦋

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🌸 SYNOPSIS 🌸

for_each_node_numadist (node , unvisited );

that's the whole vibe, she's a macro 💅

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🎀 ARGUMENTS 🎀

• node — this one's doing double duty fr: it's the iteration variable and it's your starting node. main character energy 👑
• unvisited — a nodemask that keeps track of the unvisited nodes. think of it as the "still gotta get to these" checklist 🍓

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💖 DESCRIPTION 💖

so this macro iterates over NUMA node IDs in increasing distance from the starting node, and it yields MAX_NUMNODES when all the nodes have been visited. that's the finish line, that's the credits rolling 🎬

note (and this part matters, bestie): by the time the loop completes, the unvisited nodemask will be fully cleared — unless the loop exits early. so if you bounce out of the loop mid-way, don't come crying that the mask is still messy 😭

now, the difference between for_each_node and for_each_node_numadist? iconic contrast, honestly:

• for_each_node lets you iterate over nodes in numerical order (1, 2, 3, boring but reliable ✨)
• for_each_node_numadist iterates over nodes in increasing order of distance (nearest-first, like a good friend 🫶)

the complexity of this iterator is O(N^2), where N represents the number of nodes, because each iteration involves scanning all nodes to find the one with the shortest distance. yeah, she's doing a lot of work per lap, lowkey expensive but she's worth it 🔥

⚠️ requires rcu_lock to be held. not a suggestion, not a vibe, an actual requirement — hold that lock, bestie 💀

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🌈 SEE ALSO 🌈

• Kernel file ./include/linux/topology.h
• for_each_numa_hop_mask(9)

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okay that's the page!! this one lives in ./include/linux, dated October 2026, and it's been a whole journey — stay locked, stay close to your nodes, and slay 💜🧚⭐