Compression Scheme of Log-Based Architectures

Tuesday February 19, 2008
Hamerschlag Hall D-210
4:00 pm

Theodoros Strigkos
Carnegie Mellon University

Runtime monitoring tools are invaluable for detecting various types of bugs, yet rarely used for deployed code as they impose significant overheads on the monitored application. Log-Based Architectures is an architectural approach that advocates utilizing otherwise idle cores in a CMP to dramatically reduce the overheads for runtime program monitoring. In order to achieve this, the main program’s trace is logged and delivered to the monitoring core for inspection; however, the bandwidth required for the log transport easily exceeds the bandwidth offered by available on-chip interconnects.

In this talk, I will present the value-prediction based compression scheme of Log-Based Architectures that reduces the log-related bandwidth and storage requirements by an order of magnitude. The main innovation over previous value-prediction compressors is the use of mechanisms that allow for nearly random access in the compressed stream as well as the introduction of techniques such as half prediction and default stride prediction that reduce the misprediction rate and penalty, resulting to a compressed stream that requires less than 1 byte per instruction.

Theodoros Strigkos is a Ph.D. student advised by Professor Babak Falsafi and Professor Todd Mowry in Electrical and Computer Engineering at Carnegie Mellon University. He received his Diploma in Engineering from the National Technical University of Athens, Greece. He is mainly interested in the area of computer architecture.