Deadlock-free joins in DB-mesh, an asynchronous systolic array accelerator

Bingyi Cao, Kenneth A. Ross, Stephen A. Edwards, Martha A. Kim
2017 Proceedings of the 13th International Workshop on Data Management on New Hardware - DAMON '17  
Previous database accelerator proposals such as the Q100 provide a fixed set of database operators, chosen to support a target query workload. Some queries may not be well-supported by a fixed accelerator, typically because they need more resources/operators of a particular kind than the accelerator provides. By Amdahl's law, these queries become relatively more expensive as they are not fully accelerated. We propose a second-level accelerator, DB-Mesh, to take up some of this workload. DB-Mesh
more » ... is an asynchronous systolic array that is more generic than the Q100, and can be configured to run a variety of operators with configurable parameters such as record widths. We demonstrate DB-Mesh applied to nested loops joins, an operator that is not directly supported on the Q100. We show that a naïve implementation has the potential for deadlock, and show how to avoid deadlock with a careful design. We also demonstrate how the data flow policy used in the array influences system throughput.
doi:10.1145/3076113.3076118 dblp:conf/damon/CaoREK17 fatcat:fyt6jnrnzbgmxb5uknvj2xkepe