A workload scheduler detects a long-running job when its duration exceeds a threshold value calculated by applying a multiplication factor to an estimated duration of the job. An operator inputs two extreme values of the multiplication factor, which consist of an upper level for the short-duration jobs and a lower level for the long-duration jobs. An algorithm then calculates the appropriate multiplication factor for any particular job, giving much more weight to the upper level when the estimated duration is small, but which gradually swings the levels to give more importance to the lower level when the estimated duration is long.