Sometimes the comparison shows that actual usage is well below targeted usage. In such a case, the adjusting of a user's share or a project's share of resource can allow a user to dominate the system. Such an adjustment is based on the goal of reaching target share. This domination might not be desirable.
The compensation factor enables an administrator to limit how much a user or a project can dominate the resources in the near term.
For example, a compensation factor of two limits a user's or project's current share to twice its targeted share. Assume that a user or a project should get 20 percent of the system resources over the accumulation period. If the user or project currently gets much less, the maximum it can get in the near term is only 40 percent.
The share-based policy defines long-term resource entitlements of users or projects as per the share tree. When combined with the share-based policy, the compensation factor makes automatic adjustments in entitlements.
If a user or project is either under or over the defined target entitlement, the grid engine system compensates. The system raises or lowers that user's or project's entitlement for a short term over or under the long-term target. This compensation is calculated by a share tree algorithm.
The compensation factor provides an additional mechanism to control the amount of compensation that the grid engine system assigns. The additional compensation factor (CF) calculation is carried out only if the following conditions are true:
Short-term-entitlement is greater than long-term-entitlement multiplied by the CF
The CF is greater than 0
If either condition is not true, or if both conditions are not true, the compensation as defined and implemented by the share-tree algorithm is used.
The smaller the value of the CF, the greater is its effect. If the value is greater than 1, the grid engine system's compensation is limited. The upper limit for compensation is calculated as long-term-entitlement multiplied by the CF. And as defined earlier, the short-term entitlement must exceed this limit before anything happens based on the compensation factor.
If the CF is 1, the grid engine system compensates in the same way as with the raw share-tree algorithm. So a value of one has an effect that is similar to a value of zero. The only difference is an implementation detail. If the CF is one, the CF calculations are carried out without an effect. If the CF is zero, the calculations are suppressed.
If the value is less than 1, the grid engine system overcompensates. Jobs receive much more compensation than they are entitled to based on the share-tree algorithm. Jobs also receive this overcompensation earlier, because the criterion for activating the compensation is met at lower short-term entitlement values. The activating criterion is short-term-entitlement > long-term-entitlement * CF.