Recent research revisits pairwise-correlating data prefetching due to its extremely low overhead. Pairwise-correlating data prefetching, however, cannot accurately detect where data streams end. As a result, pairwise-correlating data prefetchers either expose low accuracy or they lose timeliness when they are performing multi-degree prefetching. In this letter, we propose a novel technique to detect where data streams end and hence, control the multi-degree prefetching in the context of pairwise-correlated prefetchers. The key idea is to have a separate metadata table that operates one step ahead of the main metadata table. This way, the runahead metadata table harnesses the degree of prefetching by allowing/disallowing the main metadata table to issue prefetch requests. We evaluate our proposal in the context of a four-core chip multiprocessor and show that it significantly reduces erroneous prefetches, providing up to 16.1 percent performance improvement on top of a state-of-the-art pairwise-correlating prefetcher.

中文翻译：

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利用 Runahead 元数据利用成对相关的数据预取

由于其极低的开销，最近的研究重新审视了成对相关的数据预取。然而，成对相关的数据预取无法准确检测数据流的结束位置。结果，成对相关的数据预取器在执行多度预取时要么暴露低精度，要么失去及时性。在这封信中，我们提出了一种新技术来检测数据流在哪里结束，从而在成对相关预取器的上下文中控制多度预取。关键思想是有一个单独的元数据表，它比主元数据表提前一步运行。这样，超前元数据表通过允许/禁止主元数据表发出预取请求来利用预取的程度。