On the Scalability of an Automatically Parallelized Irregular Application

Abstract. Irregular applications, i.e., programs that manipulate pointer-based data structures such as graphs and trees, constitute a challenging target for pa-rallelization because the amount of parallelism is input dependent and changes dynamically. Traditional dependence analysis techniques are too conservative to expose this parallelism. Even manual parallelization is difficult, time consum-ing, and error prone. The Galois system parallelizes such applications using an optimistic approach that exploits higher-level semantics of abstract data types. In this paper, we study the performance and scalability of a Galoised, that is, automatically parallelized, version of Delaunay mesh refinement (DR) on a shared-memory system with 128 CPUs. DR is an important irregular application that is used, e.g., in graphics and finite-element codes. The parallelized program scales to 64 threads, where it reaches a speedup of 25.8. For large numbers of threads, the performance is hampered by the load imbalance and the nonuniform memory latency, both of which grow as the number of threads increases. While these two issues will have to be addressed in future work, we believe our results already show the Galois approach to be very promising

Relapsing acute and chronic pancreatitis

Twenty five children with non-traumatic relapsing acute or chronic pancreatitis who had been followed up from five months to seven years were studied. Seven had congenital anomalies, including two with choledochal cysts and four with pancreas divisum. Alcohol related disease was suspected in one child. The importance of diabetes in two patients and a positive family history in a further three is discussed, but in 12 children no association was found. Management was similar to that for adults. Surgical intervention was required in six patients, and percutaneous drainage of pseudocysts in a further three. Outcome has generally been good