Error Set PerfEventOpenError [src]

Errors

DeviceBusy

Returned if another event already has exclusive access to the PMU.

EventNotSupported

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.

EventRequiresUnsupportedCpuFeature

PermissionDenied

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.

ProcessNotFound

Returned if attempting to attach to a process that does not exist.

ProcessResources

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.

SampleMaxStackOverflow

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.

SampleStackNotSupported

Returned if PERF_SAMPLE_STACK_USER is set in sample_type and it is not supported by hardware.

TooBig

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.

TooManyBreakpoints

Returned if you try to add more breakpoint events than supported by the hardware.

Unexpected UnexpectedError

The Operating System returned an undocumented error code.

This error is in theory not possible, but it would be better to handle this error than to invoke undefined behavior.

When this error code is observed, it usually means the Zig Standard Library needs a small patch to add the error code to the error set for the respective function.

Source

  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  