presto-main/src/main/java/io/prestosql/execution/scheduler/SqlQueryScheduler.java/SqlQueryScheduler/getTotalCpuTime
class SqlQueryScheduler:    public Duration getTotalCpuTime()
    {
        long millis = stages.values().stream()
                .mapToLong(stage -> stage.getTotalCpuTime().toMillis())
                .sum();
        return new Duration(millis, MILLISECONDS);
    }