I think this can be handled in Grafan as well. I can’t get to my Grafana right now for some reason but when you add the data to the graph, one of the fields lets you define a function that will let you smooth spikes like these.
Look at the Selection/Aggregation Functions section of InfluxDB+Grafana persistence and graphing for a good explanation.
I bet many would appreciate a tutorial on how to set that up. Since rrd4j is an embedded database it isn’t immediately clear how one would connect Grafana to it.