Performance bugs have classically been difficult to identify in high performance programs. The problem arises because there is a broad spectrum of causes of performance degradation, and because it may be necessary to apply specialized diagnostics to search the performance space. The prototype tuning environment we are developing enables one to explore the performance space of a program using cu...

In this paper we present a technique for visualising hierarchical and symmetric, multi-modal fitness functions that have been investigated in the evolutionary computation literature. The focus of this technique is on landscapes in moderate-dimensional, binary spaces (i.e., fitness functions defined over [0,1](n), for n < or = 16). The visualisation approach involves an unfolding of the hyperspa...

We explore a number of pragmatic principles of communication in a series of computer simulations. These principles characterize both the environment and the behavior of the interacting agents. We investigate how a common language can emerge and when it will be useful to communicate, rather than try the task without communication. When we include the cost of communicating, it becomes favorable t...

In the first international branch prediction competition, the O-GEHL branch predictor has shown to yield the highest prediction accuracy under an official limited storage budget of 64Kbits. In this paper, we propose and evaluate two alternative designs of the predictor to further improve its efficiency. The first proposed method dynamically adjusts the lengths of branch history used in its inde...