STRUCT TRACE_BUFFER_META(9)

🎀 struct trace_buffer_meta (9) — like, the Kernel API Manual page, bestie 🎀

okay so picture this: it's giving Ring-buffer Meta-page description. that's the whole vibe. ✨

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💖 NAME 💖

struct trace_buffer_meta — the ring-buffer meta-page description, and yes it's exactly as iconic as it sounds 🫶

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🌸 SYNOPSIS 🌸

struct trace_buffer_meta {
    __u32 meta_page_size;
    __u32 meta_struct_len;
    __u32 subbuf_size;
    __u32 nr_subbufs;
    struct {
      __u64 lost_events;
      __u32 id;
      __u32 read;
    } reader;
    __u64 flags;
    __u64 entries;
    __u64 overrun;
    __u64 read;
    __u64 pages_lost;
    __u64 pages_touched;
 };

like, that's the whole struct. no cap, that's it 💅

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🦋 Members 🦋

okay bestie, field-by-field, let's go 👑

• meta_page_size — the size of this meta-page. that's the number, periodt ✨
• meta_struct_len — the size of this structure itself. self-aware king 🌈
• subbuf_size — the size of each sub-buffer 💜
• nr_subbufs — the number of subbfs in the ring-buffer, including the reader. (yes, "subbfs" — we don't edit the source, we respect the source 😭)
• reader — the reader composite info structure, a little struct inside the struct, main character energy 🎀
  • reader.lost_events — number of events lost at the time of the reader swap 💀
  • reader.id — subbuf ID of the current reader. ID range [0 : nr_subbufs - 1] ⭐
  • reader.read — number of bytes read on the reader subbuf 🍓
• flags — placeholder for now, 0 until new features are supported. it's lowkey just vibing there 🙈
• entries — number of entries in the ring-buffer 🔥
• overrun — number of entries lost in the ring-buffer 😭
• read — number of entries that have been read 👑
• pages_lost — number of pages overwritten by the writer 💅
• pages_touched — number of pages written by the writer ✨

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🌟 SEE ALSO 🌟

• Kernel file ./include/uapi/linux/trace_mmap.h — go read it, iykyk 🧚

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💖 friendly reminder bestie: flags is literally a placeholder for now, 0 until new features are supported — so don't go building your whole personality on it yet 🫶

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and that's a wrap, gorgeous ✨ this little gem lives in ./include/uapi/linux, dated October 2026 — so like, slightly future-core of it, and honestly? slay. 💜🦋🎀