STRUCT MSM_PERFCNTR_STATE(9)

💜 struct msm_perfcntr_state(9) — the whole global perfcntr vibe

okay bestie, so this is a page from the Kernel API Manual — section 9, kernel API, we love a niche corner of the docs ✨ — and today's main character is struct msm_perfcntr_state, which is the overall global perfcntr state. that's the whole assignment. she's global, she's a struct, she holds the perfcntr situation together. periodt 💅

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🎀 SYNOPSIS 🎀

like, literally, this is her:

struct msm_perfcntr_state {
    struct msm_perfcntr_stream *stream;
    uint32_t sel_seqno;
    struct msm_perfcntr_group_state *groups[];
};

no cap, that's it. three fields and a lot of responsibility 🫶

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🌸 Members 🌸

okay let's go field by field, i'm obsessed with each of them:

• stream — the current global counter stream, but only if active bestie. if it's not active, she's not streaming, that's the whole point 🙈
• sel_seqno — a counter for sel_fence. that's her job. counting. for the fence. iconic behavior honestly ⭐
• groups — the Global perfcntr stream group state</> 🦋 that's the state of the stream groups, globally. yes queen.

🧚 the lore (a.k.a. why she exists like this)

so, conceptually, this thing is part of msm_perfcntr_stream state. like emotionally, she belongs to the stream. but she doesn't live there, because she's statically pre-allocated when the gpu is initialized — and the reason is genuinely so real:

it simplifies error path cleanup in the PERFCNTR_CONFIG ioctl 💀 because as the docs literally put it: __free(kfree) doesn't really help with variable length arrays of allocated pointers. and that's the truth, ngl. the cleanup would be a whole mess, so we just don't go there. static allocation. slay.

lowkey important: the "conceptually part of msm_perfcntr_stream state" thing is the actual explanation from the page — she's not physically in that struct, she's just spiritually adjacent, and the pre-allocation at gpu init is why. iykyk 🎀

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🔥 SEE ALSO 🔥

go read these next, bestie, they're the friend group:

• Kernel file ./drivers/gpu/drm/msm/msm_gpu.h — the file, yes, the whole file, go look at it 📁
• struct msm_gpu_devfreq(9)
• struct msm_perfcntr_group_state(9)
• struct msm_context(9)
• msm_context_is_vmbind(9)
• msm_gpu_convert_priority(9)
• struct msm_gpu_submitqueue(9)

read them in order or don't, we don't gatekeep 🌈

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mwah 💋 this page lives in ./drivers/gpu/drm/msm, it's from October 2026, and it's the struct msm_perfcntr_state(9) page — tag yourself, i'm the variable length array of allocated pointers that nobody wants to free 🍓✨