PerfEventOpenError

pub const PerfEventOpenError = error{
    /// Returned if the perf_event_attr size value is too small (smaller
    /// than PERF_ATTR_SIZE_VER0), too big (larger than the page  size),
    /// or  larger  than the kernel supports and the extra bytes are not
    /// zero.  When E2BIG is returned, the perf_event_attr size field is
    /// overwritten by the kernel to be the size of the structure it was
    /// expecting.
    TooBig,
    /// Returned when the requested event requires CAP_SYS_ADMIN permis‐
    /// sions  (or a more permissive perf_event paranoid setting).  Some
    /// common cases where an unprivileged process  may  encounter  this
    /// error:  attaching  to a process owned by a different user; moni‐
    /// toring all processes on a given CPU (i.e.,  specifying  the  pid
    /// argument  as  -1); and not setting exclude_kernel when the para‐
    /// noid setting requires it.
    /// Also:
    /// Returned on many (but not all) architectures when an unsupported
    /// exclude_hv,  exclude_idle,  exclude_user, or exclude_kernel set‐
    /// ting is specified.
    /// It can also happen, as with EACCES, when the requested event re‐
    /// quires   CAP_SYS_ADMIN   permissions   (or   a  more  permissive
    /// perf_event paranoid setting).  This includes  setting  a  break‐
    /// point on a kernel address, and (since Linux 3.13) setting a ker‐
    /// nel function-trace tracepoint.
    PermissionDenied,
    /// Returned if another event already has exclusive  access  to  the
    /// PMU.
    DeviceBusy,
    /// Each  opened  event uses one file descriptor.  If a large number
    /// of events are opened, the per-process limit  on  the  number  of
    /// open file descriptors will be reached, and no more events can be
    /// created.
    ProcessResources,
    EventRequiresUnsupportedCpuFeature,
    /// Returned if  you  try  to  add  more  breakpoint
    /// events than supported by the hardware.
    TooManyBreakpoints,
    /// Returned  if PERF_SAMPLE_STACK_USER is set in sample_type and it
    /// is not supported by hardware.
    SampleStackNotSupported,
    /// Returned if an event requiring a specific  hardware  feature  is
    /// requested  but  there is no hardware support.  This includes re‐
    /// questing low-skid events if not supported, branch tracing if  it
    /// is not available, sampling if no PMU interrupt is available, and
    /// branch stacks for software events.
    EventNotSupported,
    /// Returned  if  PERF_SAMPLE_CALLCHAIN  is   requested   and   sam‐
    /// ple_max_stack   is   larger   than   the  maximum  specified  in
    /// /proc/sys/kernel/perf_event_max_stack.
    SampleMaxStackOverflow,
    /// Returned if attempting to attach to a process that does not  exist.
    ProcessNotFound,
} || UnexpectedError