PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER
flags |= PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER;
is_unregister = (event->ksymbol.flags & PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER);
if (event->ksymbol.flags & PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER)