Dynamic Computation Migration in DSM Systems

Dynamic computation migration is the runtime choice between computation and data migration. Dynamic computation migration speeds up access to concurrent data structures with unpredictable read/write patterns. This paper describes the design, implementation, and evaluation of dynamic computation migration in a multithreaded distributed shared-memory system, MCRL. Two policies are studied, STATIC and REPEAT. Both migrate computation for writes. STATIC migrates data for reads, while REPEAT maintains a limited history of accesses and sometimes migrates computation for reads. On a concurrent, distributed B-tree with 50% lookups and 50% inserts, STATIC improves performance by about 17% on both Alewife and the CM-5. REPEAT generally performs better than STATIC. With 80% lookups and 20% inserts, REPEATimproves performance by 23% on Alewife, and by 46% on the CM-5.