

Current fairshare database. Current state at 2014/12/02 09:40 The table below represents the fairshare database on past usage on the cluster which is used as a component in calculating jobpriorities for queued jobs. Read about the scheduling strategy. The table has for each group:
The last 2 rows has the total usage in CPUhours and utilization in % for each of the fairshare windows. Note that the utilization usually hovers around 90%, even though the queue is never empty  please read the document "Horseshoe Utilization" for an explanation.
Some more details: A fairshare window represents statistics for the cluster in a timeslice of 8 days and 8 hours, except for window1 which can only represent stats for a maximum of 8 days and 8 hours. After this period of time window1 stats is rolled to window2, window2 stats to window3, etc. The current Window1 expires on 04/12/2014 09:00. The maximum total use in a fairshare window can thus be 263*(8*24 + 8)hours = 52600 CPUhours. The weighted use for a given group is calculated by weighting the use per fairshare window with a decayrate (in our case 0.8). It's calculated as the fraction Nu/De with: De = sum_{i=1}^{i=5} [TU(i)*0.8^{i}], where TU(i) is total usage in window number i. Nu = sum_{i=1}^{i=5} [TU(i)*0.8^{i}*Win(i)], where Win(i) is the given groups % usage in window number i. Knowing the weighted use for a given group, jobs submitted by members of this this group will have jobpriorities for queued jobs offset by a term DFS = FS_weight*(Target Use  Weighted Use), where FS_weight has been set to 1600. The final piece of input to the calculation of the priority for a queued job is the time spend in queue measured in minutes (Queue_time). The priority is then: priority = 80000 + Min(DFS,8640) + 1*Queue_time The calculation Min(DFS,8640) is done to ensure that a job cannot gain a priorityboost of more than the equivalent of waiting 6 days in queue, due to an underutilization of the allotted group (or user) fairshare. Users in group other. The users in the group other have priorities calculated in a similar manner, except that the Target Use and Weighted Use is calculated on a per user basis, not group basis. The table below show the same stats for these users, as is shown for the groups above. FS_weight has been set to 4800 for the calculation of priority offsets for these users.

