6 research outputs found
Improvement Energy Efficiency for a Hybrid Multibank Memory in Energy Critical Applications
High performance, low power multiprocessor/multibank memory system requires a compiler that provides efficient data partitioning and mapping procedures. This paper introduced two compiler techniques for the data mapping to multibank memory, since data mapping is still an open problem and needs a better solution. The multibank memory can be consisted of volatile and non-volatile memory components to support ultra-low powered wearable devices. This hybrid memory system including volatile and non-volatile memory components yields higher complexity to map data onto it. To efficiently solve this mapping problem, we formulate it to a simple decision problem. Based on the problem definition, we proposed two efficient algorithms to determine the placement of data to the multibank memory. The proposed techniques consider the characteristic of the non-volatile memory that its write operation consumes more energy than the same operation of a volatile memory even though it provides ultra-low operation power and nearly zero leakage current. The proposed technique solves this negative effect of non-volatile memory by using efficient data placement technique and hybrid memory architecture. In experimental section, the result shows that the proposed techniques improve energy saving up to 59.5% for the hybrid multibank memory architecture
Adaptive Merging on Phase Change Memory
Indexing is a well-known database technique used to facilitate data access
and speed up query processing. Nevertheless, the construction and modification
of indexes are very expensive. In traditional approaches, all records in the
database table are equally covered by the index. It is not effective, since
some records may be queried very often and some never. To avoid this problem,
adaptive merging has been introduced. The key idea is to create index
adaptively and incrementally as a side-product of query processing. As a
result, the database table is indexed partially depending on the query
workload. This paper faces a problem of adaptive merging for phase change
memory (PCM). The most important features of this memory type are: limited
write endurance and high write latency. As a consequence, adaptive merging
should be investigated from the scratch. We solve this problem in two steps.
First, we apply several PCM optimization techniques to the traditional adaptive
merging approach. We prove that the proposed method (eAM) outperforms a
traditional approach by 60%. After that, we invent the framework for adaptive
merging (PAM) and a new PCM-optimized index. It further improves the system
performance by 20% for databases where search queries interleave with data
modifications
Towards Successful Application of Phase Change Memories: Addressing Challenges from Write Operations
The emerging Phase Change Memory (PCM) technology is drawing increasing attention due to its advantages in non-volatility, byte-addressability and scalability. It is regarded as a promising candidate for future main memory. However, PCM's write operation has some limitations that pose challenges to its application in memory. The disadvantages include long write latency, high write power and limited write endurance.
In this thesis, I present my effort towards successful application of PCM memory. My research consists of several optimizing techniques at both the circuit and architecture level. First, at the circuit level, I propose Differential Write to remove unnecessary bit changes in PCM writes. This is not only beneficial to endurance but also to the energy and latency of writes. Second, I propose two memory scheduling enhancements (AWP and RAWP) for a non-blocking bank design. My memory scheduling enhancements can exploit intra-bank parallelism provided by non-blocking bank design, and achieve significant throughput improvement. Third, I propose Bit Level Power Budgeting (BPB), a fine-grained power budgeting technique that leverages the information from Differential Write to achieve even higher memory throughput under the same power budget. Fourth, I propose techniques to improve the QoS tuning ability of high-priority applications when running on PCM memory.
In summary, the techniques I propose effectively address the challenges of PCM's write operations. In addition, I present the experimental infrastructure in this work and my visions of potential future research topics, which could be helpful to other researchers in the area