Understanding and Improving Bloom Filter Configuration for Lazy Address-Set Disambiguation

Understanding and Improving Bloom Filter Configuration for Lazy Address-Set Disambiguation Mark C. Jeffrey Master of Applied Science Graduate Department of Electrical and Computer Engineering University of Toronto 2011 Many parallelization systems detect memory access conflicts across concurrent threads by disambiguating address-sets using bit-vector-based Bloom filters, which are efficient, but can report false conflicts that do not exist. Systems with lazy conflict detection often use Bloom filters unconventionally by testing sets for null-intersection via Bloom filter intersection, contrasting with the conventional approach of issuing membership queries into the Bloom filter. In this dissertation we develop much-needed theory for probability of false conflicts in Bloom filter null-intersection tests, notably demonstrating that Bloom filter intersection requires substantially larger bit-vectors to provide equivalent statistical behavior to querying. Furthermore, we recognize that our theoretical implications counter practical intuition, and thus use RingSTM to evaluate theory in practice by implementing and comparing the Bloom filter configurations. We find that despite its overheads, the queue-of-queries approach reduces execution time and is thus the most compelling alternative to Bloom filter intersection for lazy address-set disambiguation.