DAG-consistent distributed shared memory

Introduces DAG (directed acyclic graph) consistency, a relaxed consistency model for distributed shared memory which is suitable for multithreaded programming. We have implemented DAG consistency in software for the Cilk multithreaded runtime system running on a CM5 Connection Machine. Our implementation includes a DAG-consistent distributed cactus stack for storage allocation. We provide empirical evidence of the flexibility and efficiency of DAG consistency for applications that include blocked matrix multiplication, Strassen´s (1969) matrix multiplication algorithm and a Barnes-Hut code. Although Cilk schedules the executions of these programs dynamically, their performances are competitive with statically scheduled implementations in the literature. We also prove that the number F_P of page faults incurred by a user program running an P processors can be related to the number F₁ of page faults running serially by the formula F_P⩽F₁+2Cs, where C is the cache size and s is the number of thread migrations executed by Cilk´s scheduler