Dear users of the SuperMUC Petaflop System at LRZ, with recent updates to LoadLeveler, new features have become available that support an improved energy savings model on the thin islands of the system. As a consequence, you will in the near future need to modify your Loadleveler scripts if you wish to run your thin node jobs at a higher frequency than the standard value of 2.3 GHz. There are two required items you need to enter in all your LoadLeveler scripts: 1. You need to generate an energy tag for your job using the #@ energy_policy_tag = <tag name> notation; this energy tag will after the first run of that job contain the information Loadleveler needs to estimate whether a performance advantage can be gained at sufficiently low cost. 2. You need to specify the keyword #@ minimize_time_to_solution = yes to request a frequency increase from LoadLeveler. Without this item, all jobs will run at the standard frequency of 2.3 GHz. If both the above are fulfilled, LoadLeveler will set the CPU frequency for all nodes of the job according to following criteria, applied in order of appearance: * If run time using 2.4 GHz is expected to decrease by more than 2.5% compared to 2.3 GHz, the frequency is set to 2.4 GHz * If run time using 2.5 GHz is expected to decrease by more than 5% compared to 2.3 GHz, the frequency is set to 2.5 GHz * If run time using 2.6 GHz is expected to decrease by more than 8.5% compared to 2.3 GHz, the frequency is set to 2.6 GHz * If run time using 2.7 GHz is expected to decrease by more than 12% compared to 2.3 GHz, the frequency is set to 2.7 GHz This new energy management policy will be activated on October 7, 2013 at 10:00 am. We encourage all users of the system to make use of this new feature to accelerate processing of jobs. Please note that after this change, the previously supported keyword max_perf_decrease_allowed will not have any effect any more; jobs still using this keyword will be rejected at submission time from January 2014 onward. For further details, please also consult http://www.lrz.de /services/compute/supermuc/loadleveler/#energy which will be updated on the same date the change is performed. This information is also available on our web server http://www.lrz-muenchen.de/services/compute/supermuc/aktuell/ali4667/ Reinhold Bader