The following paper will be discussed in the seminar on Tuesday October 29 ,2002 in CME 345

Memory access scheduling

Proceedings of the 27th annual international symposium on Computer architecture

2000 , Vancouver, British Columbia, Canada

Authers:

Scott Rixner
William J. Dally
Ujval J. Kapasi
Peter Mattson
John D. Owens

Computer systems Laboratory

Stanford University

Stanford CA 94305

ABSTRACT

The bandwidth and latency of a memory system are strongly dependent on the manner in which accesses interact with the “3-D” structure of banks, rows, and columns characteristic of contemporary DRAM chips. There is nearly an order of magnitude difference in bandwidth between successive references to different columns within a row and different rows within a bank. This paper introduces memory access scheduling, a technique that improves the performance of a memory system by reordering memory references to exploit locality within the 3-D memory structure. Conservative reordering, in which the first ready reference in a sequence is performed, improves bandwidth by 40% for traces from five media benchmarks. Aggressive reordering, in which operations are scheduled to optimize memory bandwidth, improves bandwidth by 93% for the same set of applications. Memory access scheduling is particularly important for media processors where it enables the processor to make the most efficient use of scarce memory bandwidth.