Perf Paranoid¶

The perf_event_paranoid setting in /proc/sys/kernel/perf_event_paranoid controls access to performance monitoring features:

Value	Access Level
`-1`	No restrictions (full access).
`0`	Allow normal users access, but no raw tracepoint samples.
`1`	Allow user and kernel-level profiling (default before Linux `4.6`).
`>= 2`	Only user-level measurements allowed (default since Linux `4.6`).

If the setting is too restrictive, you may encounter errors like:

Cannot open perf counter: insufficient access rights to start the counter,
e.g., profiling a not user-owned process or perf_event_paranoid value too high.

This can be resolved by lowering the paranoid level or adjusting your monitoring configuration.

Setting the Perf Paranoid Value¶

Temporarily (until reboot):

sudo sysctl -w kernel.perf_event_paranoid=-1

Persistently, add to /etc/sysctl.conf:

kernel.perf_event_paranoid = -1

Then apply:

sudo sysctl --system

Adjusting Monitoring Configuration¶

If you cannot modify the paranoid level, disable kernel/hypervisor-level measurements to allow profiling under restrictive settings (>= 2):

auto config = perf::Config{};
config.include_kernel(false);       /// Disable kernel event recording.
config.include_hypervisor(false);   /// Disable hypervisor event recording.

auto event_counter = perf::EventCounter{ config };
event_counter.add({"instructions", "cycles"});

event_counter.start(); /// Will only record user-level events.

To further restrict monitoring, exclude guest events:

config.include_guest(false);