Adaptive transaction scheduling for mixed transactional workloads

Abstract

Optimistic scheduling policy based on the concept of Very Important Transaction.Progressively pessimistic scheduling policy with low runtime overheads.Adaptive scheduler that combines two scheduling policies in a synergistic way.Thorough evaluation of 4 schedulers with the STAMP and the STMBench7 benchmark. Transaction schedulers reduce the number of transaction reexecutions in applications using Software Transactional Memory (STM) by preventing conflicting transactions to run in parallel. Unfortunately, current scheduling solutions are too conservative, rely on coarse measures to serialize transactions, and are specially inadequate for workloads with long transactions.In this paper we introduce an optimistic and adaptive transaction scheduler that takes advantage of the information already collected by the STM runtime to increase parallelism between transactions and, thus, improve transactions' throughput. Our new ProVIT scheduler implements a low-overhead scheduling policy for short transactions that reduces concurrency as contention increases and a fine-grained scheduling policy for long transactions based on the novel concept of Very Important Transaction.Experimental results conducted with the STMBench7 benchmark and the STAMP benchmark suite showed that the ProVIT scheduler has comparable performance to other current scheduling solutions for short transactions, but is up to 65% faster for long-running transactions.