message: if no gpu, don't create device tracer.
diff: @@ -1348,7 +1348,7 @@ absl::string_view AnnotationMap::LookUp(uint32 device_id,
  }
  bool CuptiTracer::IsAvailable() const {
  - return !activity_tracing_enabled_ && !api_tracing_enabled_;
  + return NumGpus() && !activity_tracing_enabled_ && !api_tracing_enabled_;
  }
  int CuptiTracer::NumGpus() {
  