FusionCache: using LLC Tags for DRAM Cache
Paper in proceedings, 2018

DRAM caches have been shown to be an effective way to utilize the bandwidth and capacity of 3D stacked DRAM. Although they can capture the spatial and temporal data locality of applications, their access latency is still substantially higher than conventional on-chip SRAM caches. Moreover, their tag access latency and storage overheads are excessive. Storing tags for a large DRAM cache ill SRAM is impractical as it would occupy a significant fraction of the processor chip. Storing them in the DRAM itself incurs high access overheads. Attempting to cache the DRAM tags on the processor adds a constant delay to the access time. In this paper, we introduce FusionCache, a DRAM cache that offers more efficient tag accesses by fusing DRAM cache tags with the tags of the on-chip Last Level Cache (LLC). We observe that, in an inclusive cache model where the DRAM cachelines are multiples of on-chip SRAM cachelines, LLC tags could be re-purposed to access a large part of the DRAM cache contents. Then, accessing DRAM cache tags incurs zero additional latency in the common case.

Author

Evangelos Vasilakis

Chalmers, Computer Science and Engineering (Chalmers), Computer Engineering (Chalmers)

Vassilis Papaefstathiou

Foundation for Research and Technology Hellas (FORTH)

Pedro Petersen Moura Trancoso

Chalmers, Computer Science and Engineering (Chalmers), Computer Engineering (Chalmers)

Ioannis Sourdis

Chalmers, Computer Science and Engineering (Chalmers), Computer Engineering (Chalmers)

PROCEEDINGS OF THE 2018 DESIGN, AUTOMATION & TEST IN EUROPE CONFERENCE & EXHIBITION (DATE)

1530-1591 (ISSN)

593-596

Design, Automation and Test in Europe Conference and Exhibition (DATE)
Dresden, Germany,

Energy-efficient Heterogeneous COmputing at exaSCALE (ECOSCALE)

European Commission (Horizon 2020), 2015-10-01 -- 2018-12-31.

Subject Categories

Computer Engineering

Telecommunications

Communication Systems

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7/6/2018 8