Working Set is a term coined by Dr. Peter Denning to describe the amount of memory actually required for the execution of a program within a reasonable time period. Multics does not exactly follow this definition since the amount of memory that can be allocated to the desires of the process is constrained by physical limits and the actions of other processes. A better term would be Workable Set (the amount of memory permitted to be used), but since Multics documentation uses 'working set' it will be used in this paper.



Note 2 Correspondingly, an absentee process, which is in a work class that does not have sufficient guarantees to hold its pages, will appear to have a working set that is larger than is the case and will be discriminated against, out of proportion to its true size.

This is a noticeable positive feedback in the control system tending to degrade performance.



Note 3 An additional plus that controlled eligibilities has done for us is to enable the increase of 'maxe' to permit more effective multi-programming, and thus to drop the 'MP idle' which would otherwise run 5-20%.

In the time since this paper was originally published theories have been somewhat improved. The greatest usefulness of the 'wc_max_eligible' is really in increasing the loop time required for the restricted work classes, so that they compete more equally with the other work classes that have more processes in them. This evens the paging demands of processes and brings out the workable set requirements more accurately.