Hybrid2: Combining Caching and Migration in Hybrid Memory Systems
Preprint, 2019

This paper considers a hybrid memory system composed of memory technologies with different characteristics; in particular a small, near memory exhibiting high bandwidth, i.e., 3D-stacked DRAM, and a larger, far memory offering capacity at lower bandwidth, i.e., off-chip DRAM. In the past,
the near memory of such a system has been used either as a DRAM cache or as part of a flat address space combined with a migration mechanism.
Caches and migration offer different tradeoffs (between performance, main memory capacity, data transfer costs, etc.) and share similar challenges related to
data-transfer granularity and metadata management.
This paper proposes Hybrid2 , a new hybrid memory system architecture that combines a DRAM cache with a migration scheme. Hybrid 2 does not deny valuable capacity from the memory system because it uses only a small fraction of the near memory as a DRAM cache; 64MB in our experiments.
It further leverages the DRAM cache as a staging area to select the data most suitable for migration.
Finally, Hybrid2 alleviates the metadata overheads of both DRAM caches and migration using a common mechanism.
Using near to far memory ratios of 1:16, 1:8 and 1:4 in our experiments, Hybrid2 on average outperforms current state-of-the-art migration schemes by 7.9%, 9.1% and 6.4%, respectively.
In the same system configurations, compared to DRAM caches Hybrid2 gives away on average only 0.3%, 1.2%, and 5.3% of performance offering 5.9%, 12.1%, and 24.6% more main memory capacity, respectively.

Hybrid Memory Systems

DRAM caches

Data Migration

Författare

Evangelos Vasilakis

Chalmers, Data- och informationsteknik, Datorteknik, Computer Systems

Vasileios Papaefstathiou

Chalmers, Data- och informationsteknik, Datorteknik

Pedro Petersen Moura Trancoso

Chalmers, Data- och informationsteknik, Datorteknik, Computer Systems

Ioannis Sourdis

Chalmers, Data- och informationsteknik, Datorteknik, Computer Systems

Ämneskategorier

Datorteknik

Inbäddad systemteknik

Datorsystem

Styrkeområden

Informations- och kommunikationsteknik

Infrastruktur

C3SE (Chalmers Centre for Computational Science and Engineering)

Mer information

Skapat

2019-08-28