STRUCT PERF_MMAP(9)

okay bestie, welcome to the struct perf_mmap(9) glow-up 💅 this one lives in the Kernel API Manual, and it's basically the little receipt for perf's ring buffer mmap details. it's short, it's sweet, it's giving "entry-level struct with main character energy" 🎀 let's get into it.

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🌸 NAME 🌸

struct perf_mmap — the whole vibe of perf's ring buffer mmap details ✨

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🦋 SYNOPSIS 🦋

okay so here's the actual struct, and yes you're gonna read every line of it because we don't skip 💖

struct perf_mmap {
    void *base;
    int mask;
    int fd;
    struct perf_cpu          cpu;
    refcount_t refcnt;
    u64 prev;
    u64 start;
    u64 end;
    bool overwrite;
    u64 flush;
    libperf_unmap_cb_t unmap_cb;
    void *event_copy;
    size_t event_copy_sz;
    struct perf_mmap        *next;
 };

look at all those fields just sitting there, living their truth 🌈 base, mask, fd, cpu, refcnt, prev, start, end, overwrite, flush, unmap_cb, event_copy, event_copy_sz, next — iconic lineup, no notes 👑

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🧚 Members 🧚

yep, this section is literally just titled Members. short king behavior 💀

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💜 Description 💜

here's the one (1) description this page actually gives us, and we're gonna treat it with the respect it deserves:

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

that's it, that's the note 🫶 like, that's the entire description section. ngl she's mysterious. we love a withholding icon 😭

bestie, real talk: this page only documents refcnt. don't go making up lore for the other fields — if it's not written here, it's not written here 🙈

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⭐ SEE ALSO ⭐

go look at the kernel file, that's where the rest of the story lives:

• Kernel file ./tools/lib/perf/include/internal/mmap.h 🔥

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and that's the whole page, bestie! 🎀 this adorable little drop came from ./tools/lib/perf/include/internal, dated October 2026 — screenshot it, cite it, send it to the group chat, periodt 💅✨🍓