perf_event_mmap_page

pub const perf_event_mmap_page = extern struct {
    /// Version number of this struct
    version: u32,
    /// Lowest version this is compatible with
    compt_version: u32,
    /// Seqlock for synchronization
    lock: u32,
    /// Hardware counter identifier
    index: u32,
    /// Add to hardware counter value
    offset: i64,
    /// Time the event was active
    time_enabled: u64,
    /// Time the event was running
    time_running: u64,
    capabilities: packed struct(u64) {
        /// If kernel version < 3.12
        /// this rapresents both user_rdpmc and user_time (user_rdpmc | user_time)
        /// otherwise deprecated.
        bit0: bool,
        /// Set if bit0 is deprecated
        bit0_is_deprecated: bool,
        /// Hardware support for userspace read of performance counters
        user_rdpmc: bool,
        /// Hardware support for a constant non stop timestamp counter (Eg. TSC on x86)
        user_time: bool,
        /// The time_zero field is used
        user_time_zero: bool,
        /// The time_{cycle,mask} fields are used
        user_time_short: bool,
        ____res: u58,
    },
    /// If capabilities.user_rdpmc
    /// this field reports the bit-width of the value read with rdpmc() or equivalent
    pcm_width: u16,
    /// If capabilities.user_time the following fields can be used to compute the time
    /// delta since time_enabled (in ns) using RDTSC or similar
    time_shift: u16,
    time_mult: u32,
    time_offset: u64,
    /// If capabilities.user_time_zero the hardware clock can be calculated from
    /// sample timestamps
    time_zero: u64,
    /// Header size
    size: u32,
    __reserved_1: u32,
    /// The following fields are used to compute the timestamp when the hardware clock
    /// is less than 64bit wide
    time_cycles: u64,
    time_mask: u64,
    __reserved: [116 * 8]u8,
    /// Head in the data section
    data_head: u64,
    /// Userspace written tail
    data_tail: u64,
    /// Where the buffer starts
    data_offset: u64,
    /// Data buffer size
    data_size: u64,
    // if aux is used, head in the data section
    aux_head: u64,
    // if aux is used, userspace written tail
    aux_tail: u64,
    // if aux is used, where the buffer starts
    aux_offset: u64,
    // if aux is used, data buffer size
    aux_size: u64,
}