proc_buddyinfo(5)

💖 proc_buddyinfo(5) — the group chat edition

okay bestie, so this is proc_buddyinfo(5) — a File Formats Manual page, section 5, all about one very specific little file that lives in /proc. no cap, it's niche but it's iconic. 💅

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✨ NAME ✨

/proc/buddyinfo — memory fragmentation 🧩

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🌸 DESCRIPTION 🌸

🫶 /proc/buddyinfo

so this file is giving diagnostic queen 💅 — it's literally the file you go look at when you're trying to figure out why memory is all fragmented and messy.

Here's the vibe of every line: it starts with the identification of the node plus the name of the zone, and those two together identify a memory region. then, after that, you get the count of available chunks of a certain order — the orders being the sizes your zones get split into.

and the size in bytes of any given order? it's this little formula, super simple, no drama:

(2^order) * PAGE_SIZE

so what's actually happening under the hood: the binary buddy allocator algorithm inside the kernel is out here splitting one chunk into two chunks of a smaller order (so, half the size each) — or doing the reverse, combining two contiguous chunks into one larger chunk of a higher order (so, double the size). it does all this to satisfy allocation requests and to counter memory fragmentation. main character energy tbh. ✨

and the order matches the column number, when you start counting at zero. yes, zero. programmers, am I right 😭

for example, on an x86-64 system:

Node 0, zone     DMA     1    1    1    0    2    1    1    0    1    1    3
Node 0, zone   DMA32    65   47    4   81   52   28   13   10    5    1  404
Node 0, zone  Normal   216   55  189  101   84   38   37   27    5    3  587

so in this example: there is one node containing three zones, and there are 11 different chunk sizes. 🫡

if the page size is 4 kilobytes, then the first zone — the one called DMA (on x86 that's the first 16 megabyte of memory) — has 1 chunk of 4 kilobytes available (that's order 0) and has 3 chunks of 4 megabytes available (that's order 10). see how the column-to-order thing works? cute. 🎀

⚠️ and here's the sad part, bestie: if the memory is heavily fragmented, the counters for the higher order chunks will be zero, and allocation of large contiguous areas will fail. 💀 like it's over. not a vibe.

if you want the further lore about the zones themselves, that's all in /proc/zoneinfo. go read it, iykyk. 🦋

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🔥 SEE ALSO 🔥

• proc(5)

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and that's the page, bestie!! 💜 mwah. this one came from Linux man-pages 6.20, dated 2026-02-08 — so you know it's fresh. slay ✨🎀🫶