Error: Failure to open event 'cpu/cycles/Pu' on PMU 'cpu' which will be removed. The sys_perf_event_open() syscall failed for event (cpu/cycles/Pu): Invalid argument "dmesg | grep -i perf" may provide additional information. Error: Failure to open any events for recording. ──────────────────────────────────────────────────────────────────────── PERF ATTRIBUTION SKIPPED (ledger §10 step 6 / §E permitted skip). Reason: kernel.perf_event_paranoid=2 with no CAP_PERFMON / no sudo → sys_perf_event_open() returns EINVAL ("Failure to open any events for recording") even for own-process userspace hardware-event sampling. Neither LBR nor a dwarf fallback can be attempted without raising the paranoid level (root). This is an environment limitation, NOT an experiment failure; the §8 decision rule does not depend on perf. Expected attribution (from the design, unconfirmed): CONTROL dominated by RwLock write-guard serialization + serialize_char_node_to_disk re-walk + fsync/msync; TREATMENT by compare_exchange spin + Arc refcount + fsync. ────────────────────────────────────────────────────────────────────────