STRUCT AMD_CPUDATA(9)

💅 struct amd_cpudata(9) — like, the whole vibe

okay so bestie, welcome to the Kernel API Manual entry for struct amd_cpudata(9). this is the private CPU data situation for AMD P-State and honestly? it ate. let's get into it 🫶

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✨ NAME ✨

struct amd_cpudata — the private CPU data for AMD P-State. that's it, that's the whole name, no notes 💅

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🌸 SYNOPSIS 🌸

struct amd_cpudata {
    int cpu;
    struct freq_qos_request req[2];
    u64 cppc_req_cached;
    u64 cppc_req2_cached;
    union perf_cached perf;
    u8 prefcore_ranking;
    u8 floor_perf_cnt;
    u8 bios_floor_perf;
    u32 min_limit_freq;
    u32 max_limit_freq;
    u32 nominal_freq;
    u32 max_freq;
    u32 lowest_nonlinear_freq;
    u32 floor_freq;
    struct amd_aperf_mperf cur;
    struct amd_aperf_mperf prev;
    u64 freq;
    bool boost_supported;
    bool hw_prefcore;
    u32 policy;
    bool suspended;
    u8 epp_default_ac;
    u8 epp_default_dc;
    bool dynamic_epp;
    bool raw_epp;
    struct notifier_block power_nb;
    enum platform_profile_option current_profile;
    struct device *ppdev;
    char *profile_name;
 };

look at her. iconic struct. every single field is right there, no skips, we respect all of them 💖

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🎀 Members 🎀

okay so here's the cast, one by one, no cap:

• cpu — the CPU number. which CPU she is, basically.
• req — the constraint request to apply.
• cppc_req_cached — cached performance request hints.
• cppc_req2_cached — cached value of MSR_AMD_CPPC_REQ2. yes, the number-two register, we love a sequel.
• perf — cached performance-related data.
• prefcore_ranking — the preferred core ranking. higher value = higher priority, so like, the higher the value the more main-character the core is 👑
• floor_perf_cnt — the cached value of the number of distinct floor performance levels supported.
• bios_floor_perf — the cached value of the boot-time floor performance level from MSR_AMD_CPPC_REQ2.
• min_limit_freq — cached value of policy->min (in khz).
• max_limit_freq — cached value of policy->max (in khz).
• nominal_freq — the frequency (in khz) that mapped to nominal_perf.
• max_freq — in ideal conditions, the maximum frequency (in khz) possible frequency. ideal conditions! manifesting ✨
• lowest_nonlinear_freq — the frequency (in khz) that mapped to lowest_nonlinear_perf.
• floor_freq — cached value of the user requested floor_freq.
• cur — the difference of Aperf/Mperf/tsc count between the last and current sample.
• prev — the last Aperf/Mperf/tsc count value read from the register.
• freq — the current cpu frequency value (in khz).
• boost_supported — checks whether the Processor or SBIOS supports boost mode.
• hw_prefcore — checks whether HW supports the preferred core featue. only when hw_prefcore and the early prefcore param are true does the AMD P-State driver support the preferred core featue. so both conditions or it's a no 💀
• policy — the Cpufreq policy value.
• suspended — if the CPU core if offlined. (yes, that's the original wording, we're keeping it fr fr 🙈)
• epp_default_ac — the default EPP value for the AC power source.
• epp_default_dc — the default EPP value for the DC power source.
• dynamic_epp — whether dynamic EPP is enabled.
• raw_epp — whether the last EPP write was a raw numeric value rather than a named preference.
• power_nb — the notifier block for power events.
• current_profile — the currently selected platform profile option.
• ppdev — the device registered with the platform profile handler.
• profile_name — the name under which ppdev is registered.

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🦋 Description 🦋

so, amd_cpudata is literally the key private data for each CPU thread in AMD P-State, and it represents all the attributes and goals that AMD P-State requests at runtime. she's holding everything together. the way that one struct carries the entire runtime wishlist? obsessed 😭💜

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🌈 SEE ALSO 🌈

go peek at these, iykyk:

• Kernel file ./drivers/cpufreq/amd-pstate.h
• union perf_cached(9)
• struct amd_aperf_mperf(9)

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ok that's the whole page bestie, every field, every flag, nothing skipped 💯

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and that's a wrap! 🎀 this little masterpiece came from ./drivers/cpufreq, dated October 2026, and it's brought to you by the Kernel API Manual — see you in the next one, mwah 💋🌸