Bulk Core in a 360/67 Time-Sharing System

摘要

In time-sharing systems where programs and data move frequently between storage media, performance measured in terms of response time, availability, capacity, and generality depends on the ability of the system to move information quickly and promptly upon demand. Analysis of and early experiences with TSS/360 reveal that a drum-oriented system cannot meet the demands imposed by user tasks. Consequently, Carnegie Institute of Technology has replaced the drum on its 360/67 with Large Capacity Core Storage. A model of the drum system was constructed, and it was discovered that it could not support its maximum paging rate except under conditions which impose high system costs. It was also found that because of its rotating nature, it actually withdraws significant portions of memory from the usable main memory of the system. Bulk core, when operated with a simple core-to-core channel, has neither of these faults. It provides the added advantage that not all pages need be swapped--those which are not heavily used may be referenced directly by the CP. By operating selectively in both modes we expect nearly an order of magnitude better performance than is possible with a drum. (Author)