STRUCT MMAP(9)

🌸 NAME 🌸

okay so bestie, welcome to struct mmap(9) — literally the manual page for struct mmap, and it's all about perf's ring buffer mmap details. that's the whole vibe. 💅

this one lives in the Kernel API Manual, so yes, we're being fancy today. ✨

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✨ SYNOPSIS ✨

here's the struct in all its glory, copied exactly so you don't have to squint, no cap:

struct mmap {
    struct perf_mmap        core;
    struct auxtrace_mmap auxtrace_mmap;
  #ifdef HAVE_AIO_SUPPORT;
    struct {
      void **data;
      struct aiocb     *cblocks;
      struct aiocb     **aiocb;
      int nr_cblocks;
    } aio;
  #endif;
    struct mmap_cpu_mask    affinity_mask;
    void *data;
    struct perf_data_file *file;
    struct zstd_data      zstd_data;
 };

like… look at it. the conditional compilation? the nested anonymous struct? it's giving structured. it's giving organized. we stan a well-formed struct. 🎀

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🫶 MEMBERS 🫶

(yeah this section is just the header doing its thing — the actual tea is served downstairs 👇)

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💅 DESCRIPTION 💅

• refcnt — e.g. code using PERF_EVENT_IOC_SET_OUTPUT to share this.

and honestly? that's the note. it's a little one-liner but it matters — if you're the kind of dev passing PERF_EVENT_IOC_SET_OUTPUT around to share this thing, then refcnt is the member you care about. periodt. 🫡

fr fr though, don't sleep on the tiny descriptions — they're short but they're load-bearing. read them twice, bestie. 💜

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👀 SEE ALSO 👀

• Kernel file ./tools/perf/util/mmap.h — go read the source, it's right there, iykyk 🦋

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okay that's the page!! so iconic, so brief, and brought to you by the fine people over in ./tools/perf/util, dated October 2026 — mwah, love that for us 💖🌸🎀