Cachier: A Tool for Automatically Inserting CICO Annotations
Shared memory in a parallel computer provides programmers with the valuable abstraction of a shared address space--through which any part of a computation can access any datum. Although uniform access simplifies programming, it also hides communication, which can lead to inefficient programs. The check-in, check-out (CICO) performance model for cache-coherent, shared-memory parallel computers helps a programmer identify the communication underlying memory references and account for its cost. CICO consists of annotations that a programmer can use to elucidate communication and a model that attributes costs to these annotations. The annotations can also serve as directives to a memory system to improve program performance. Inserting CICO annotations requires reasoning about the dynamic cache behavior of a program, which is not always easy. This paper describes Cachier, a tool that automatically inserts CICO annotations into shared-memory programs. A novel feature of this tool is its use of both dynamic information, obtained from a program execution trace, as well as static information, obtained from program analysis. We measured several benchmarks annotated by Cachier by running them on a simulation of the Dir1SW cache coherence protocol, which supports these directives. The results show that programs annotated by Cachier perform significantly better than both programs without CICO annotations and programs that were annotated by hand.
Record created on 2013-12-23, modified on 2016-08-09