CRPC-TR98742-S					Revised November 1999

Title: Bandwith-Based Performance Tuning and Prediction

Authors: Chen Ding and Ken Kennedy

Submitted November 1999

Abstract:
As the speed gap widens between CPU and memory, memory hierarchy
performance has become the bottleneck for most applications.  This is due
in part to the difficulty of fully utilizing the deep and complex memory
hierarchies found on most modern machines.  In the past, various tools on
performance tuning and prediction have been developed to improve machine
utilization.  However, these tools are not effective in practice because
they either do not consider memory hierarchy zor do so with expensive and
machine-specific program simulations.  In this paper, we first demonstrate
that application performance is now primarily limited by memory bandwidth.
With this observation, we describe a new approach based on estimating and
monitoring memory bandwidth consumption, which can achieve accurate and
efficient performance tuning and prediction.  When evaluated on a
3000-line benchmark program, NAS/SP, the bandwidth-based method has
enabled a user to obtain a speedup of 1.19 by inspecting and tuning only
5% of the source code.  Furthermore its compile-time prediction of
overall execution time was within 10% of the actual running time.

-------------------------------------------------------------------------------
Chen Ding		Ken Kennedy
cding@cs.rice.edu	ken@cs.rice.edu
Department of Computer Science
Rice University