The potential for variable-granularity access tracking for optimistic parallelism

13 years 6 months ago

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Support for optimistic parallelism such as thread-level speculation (TLS) and transactional memory (TM) has been proposed to ease the task of parallelizing software to exploit the new abundance of multicores. A key requirement for such support is the mechanism for tracking memory accesses so that conflicts between speculative threads or transactions can be detected; existing schemes mainly track accesses at a single fixed granularity--i.e., at the word level, cache-line level, or page level. In this paper we demonstrate, for a hardware implementation of TLS and corresponding speculatively-parallelized SpecINT benchmarks, that the coarsest access tracking granularity that does not incur false violations varies significantly across applications, within applications, and across ranges of memory--from word-size to page size. These results motivate a variable-granularity approach to access tracking, and we show that such an approach can reduce the number of memory ranges that must be track...

Mihai Burcea, J. Gregory Steffan, Cristiana Amza

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