Performance issues in correlated branch prediction schemes

Abstract

The Western Research Laboratory (WRL) is a computer systems research group that was founded by Digital Equipment Corporation in 1982. Our focus is computer science research relevant to the design and application of high performance scientific computers. We test our ideas by designing, building, and using real systems. The systems we build are research prototypes; they are not intended to become products.There are two other research laboratories located in Palo Alto, the Network Systems Lab (NSL) and the Systems Research Center (SRC). Another Digital research group is located in Cambridge, Massachusetts (CRL).Our research is directed towards mainstream high-performance computer systems. Our prototypes are intended to foreshadow the future computing environments used by many Digital customers. The long-term goal of WRL is to aid and accelerate the development of high-performance uni-and multi-processors. The research projects within WRL will address various aspects of high-performance computing.We believe that significant advances in computer systems do not come from any single technological advance. Technologies, both hardware and software, do not all advance at the same pace. System design is the art of composing systems which use each level of technology in an appropriate balance. A major advance in overall system performance will require reexamination of all aspects of the system.We do work in the design, fabrication and packaging of hardware; language processing and scaling issues in system software design; and the exploration of new applications areas that are opening up with the advent of higher performance systems. Researchers at WRL cooperate closely and move freely among the various levels of system design. This allows us to explore a wide range of tradeoffs to meet system goals.We publish the results of our work in a variety of journals, conferences, research reports, and technical notes. This document is a research report. Research reports are normally accounts of completed research and may include material from earlier technical notes. We use technical notes for rapid distribution of technical material; usually this represents research in progress. UUCP: decpa!wrl-techreportsTo obtain more details on ordering by electronic mail, send a message to one of these addresses with the word ''help'' in the Subject line; you will receive detailed instructions.Reports and technical notes may also be accessed via the World Wide Web: http://www.research.digital.com/wrl/home.html. The Predictability of Branches in Libraries

Runtime adaptation

“…For example, Panda et al use a data alignment technique that is based on the padding of arrays in order to stabilize cache performance and maximize cache utilization, resulting in better performance [16]. Instruction alignment has also been used to improve branch prediction [6,7,11]. Using profile information, Gloy et al find they can minimize any negative runtime effects of static correlated branch prediction, and that by doing so, their technique actually performs better than traditional static branch prediction.…”