As multicore processors are deployed in mainstream computing, the need for software tools to help parallelize programs is increasing dramatically. Data-dependence profiling is an important technique to exploit parallelism in programs. More specifically, manual or automatic parallelization can use the outcomes of data-dependence profiling to guide where to parallelize in a program.However, state-of-the-art data-dependence profiling techniques are not scalable as they suffer from two major issues when profiling large and long-running applications: (1) runtime overhead and (2) memory overhead. Existing data-dependence profilers are either unable to profile large-scale applications or only report very limited information.In this paper, we propose a scalable approach to datadependence profiling that addresses both runtime and memory overhead in a single framework. Our technique, called SD 3 , reduces the runtime overhead by parallelizing the dependence profiling step itself. To reduce the memory overhead, we compress memory accesses that exhibit stride patterns and compute data dependences directly in a compressed format. We demonstrate that SD 3 reduces the runtime overhead when profiling SPEC 2006 by a factor of 4.1× and 9.7× on eight cores and 32 cores, respectively. For the memory overhead, we successfully profile SPEC 2006 with the reference input, while the previous approaches fail even with the train input. In some cases, we observe more than a 20× improvement in memory consumption and a 16× speedup in profiling time when 32 cores are used.

We present Parallel Prophet, which projects potential parallel speedup from an annotated serial program before actual parallelization. Programmers want to see how much speedup could be obtained prior to investing time and effort to write parallel code. With Parallel Prophet, programmers simply insert annotations that describe the parallel behavior of the serial program. Parallel Prophet then uses lightweight interval profiling and dynamic emulations to predict potential performance benefit. Parallel Prophet models many realistic features of parallel programs: unbalanced workload, multiple critical sections, nested and recursive parallelism, and specific thread schedulings and paradigms, which are hard to model in previous approaches. Furthermore, Parallel Prophet predicts speedup saturation resulting from memory and caches by monitoring cache hit ratio and bandwidth consumption in a serial program.We achieve very small runtime overhead: approximately a 1.2-10 times slowdown and moderate memory consumption. We demonstrate the effectiveness of Parallel Prophet in eight benchmarks in the OmpSCR and NAS Parallel benchmarks by comparing our predictions with actual parallelized code. Our simple memory model also identifies performance limitations resulting from memory system contention.

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