Dynamic Memory Adjustment for External Mergesort

Sorting is a memory intensive operation whose performance is greatly affected by the amount of memory available as work space. When the input size is unknown or available memory space varies, static memory allocation either wastes memory space or fails to make full use of memory to speed up sorting. This paper presents a method for run-time adjustment of in-memory work space for external mergesort and a policy for allocating memory among concurrent, competing sorts. Experimental results confirm that the new method enables sorts to adapt their memory usage gracefully to the actual input size and available memory space. When multiple sorts compete for memory resources, we found that sort throughput and response time are improved significantly by our policy for memory allocation combined with limiting the number of sorts processed concurrently. 1 Introduction Sorts and joins are memory intensive operations whose performance is greatly affected by the amount of main memory work space ava..