The share-based policy is implemented through a hierarchical share tree. The share tree specifies, for a moving accumulation period, how system resources are to be shared among all users and projects. The length of the accumulation period is determined by a configurable decay constant. The grid engine system bases a job's share entitlement on the degree to which each parent node in the share tree reaches its accumulation limit. A job's share entitlement is based on its leaf node share allocation, which in turn depends on the allocations of its parent nodes. All jobs associated with a leaf node split the associated shares.
The entitlement derived from the share tree is combined with other entitlements, such as entitlements from a functional policy, to determine a job's net entitlement. The share tree is allotted the total number of tickets for share-based scheduling. This number determines the weight of share-based scheduling among the four scheduling policies.
The share tree is defined during installation. The share tree can be altered at any time. When the share tree is edited, the new share allocations take effect at the next scheduling interval.