Pool directory: Efficient coherence tracking with dynamic directory allocation in many-core systems

Shukla, Sudhanshu; Chaudhuri, Mainak

doi:10.1109/iccd.2015.7357165

Cited by 7 publications

(3 citation statements)

References 36 publications

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“…The problem of this representation is that it does not adapt to the variable sharing degrees of memory blocks. Shukla and Chaudhuri employ this representation in a pool directory [17]. Also, in [27] the authors propose to design each set of a 8-way sparse directory to have six pointer ways (used to track private data) and two bit-vector ways (for keeping track of blocks with more than 1 sharer).…”

Section: Related Workmentioning

confidence: 99%

“…Interestingly, most of those applications that exhibit high occupancy in Figure 1 (such as Fft, Radix or Ocean cp) have just one sharer per entry in almost all entries. This observation is not new as it is what motivates previous approaches that use multiple entry formats to store sharing information [9] [17]. We however exploit it differently than previously done.…”

Section: Introductionmentioning

confidence: 98%

“…• It should entail as lower complexity as possible. Way combining comes with minimal cost as it avoids the complexity introduced by other proposals [7] [9] [17]. Our proposal builds atop traditional sparse directories, relies on existing replacement algorithms, and does not increase the complexity of directory operations.…”

Section: Introductionmentioning

confidence: 99%

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Way Combination for an Adaptive and Scalable Coherence Directory

Titos-Gil

Flores

Fernández-Pascual

et al. 2019

IEEE Trans. Parallel Distrib. Syst.

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Today, general-purpose commercial multicores approaching one hundred cores are already a reality and even thousand core chips are being prototyped. Maintaining coherence across such a high number of cores in these manycore architectures requires careful design of the coherence directory used to keep track of current locations of the memory blocks at the private cache level. In this work we propose a novel organization for the coherence directory that builds on the brand-new concept of way combining. Particularly, our proposal employs just one pointer per entry, which is optimal for the common case of having just one sharer. For those addresses that require more than one pointer, we have observed that in the majority of cases extra pointers could be taken from other empty ways in the same set. Thus, our proposal minimizes the storage overheads without losing the flexibility to adapt to several sharing degrees and without the complexities of other previously proposed techniques. Through detailed simulations of a 128-core architecture, we show that the way-combining directory closely approaches the performance of a non-scalable bit-vector sparse directory, and beats other scalable state-of-the-art proposals.

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Section: Related Workmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%