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The Design of A High Capacity and Energy Efficient Phase Change Main Memory

Ferreira, Alexandre Peixoto (2011) The Design of A High Capacity and Energy Efficient Phase Change Main Memory. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Higher energy-efficiency has become essential in servers for a variety of reasons that range from heavy power and thermal constraints, environmental issues and financial savings. With main memory responsible for at least 30% of the energy consumed by a server, a low power main memory is fundamental to achieving this energy efficiency DRAM has been the technology of choice for main memory for the last three decades primarily because it traditionally combined relatively low power, high performance, low cost and high density. However, with DRAM nearing its density limit, alternative low-power memory technologies, such as Phase-change memory (PCM), have become a feasible replacement. PCM limitations, such as limited endurance and low write performance, preclude simple drop-in replacement and require new architectures and algorithms to be developed. A PCM main memory architecture (PMMA) is introduced in this dissertation, utilizing both DRAM and PCM, to create an energy-efficient main memory that is able to replace a DRAM-only memory. PMMA utilizes a number of techniques and architectural changes to achieve a level of performance that is par with DRAM. PMMA achieves gains in energy-delay of up to 65%, with less than 5% of performance loss and extremely high energy gains. To address the other major shortcoming of PCM, namely limited endurance, a novel, low- overhead wear-leveling algorithm that builds on PMMA is proposed that increases the lifetime of PMMA to match the expected server lifetime so that both server and memory subsystems become obsolete at about the same time. We also study how to better use the excess capacity, traditionally available on PCM devices, to obtain the highest lifetime possible. We show that under specific endurance distributions, the naive choice does not achieve the highest lifetime. We devise rules that empower the designer to select algorithms and parameters to achieve higher lifetime or simplify the design knowing the impact on the lifetime. The techniques presented also apply to other storage class memories (SCM) memories that suffer from limited endurance.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Ferreira, Alexandre
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairMosse, Danielmosse@cs.pitt.eduMOSSE
Committee MemberChilders, Brucechilders@cs,
Committee MemberYousif,
Committee MemberMelhem, Ramimelhem@cs.pitt.eduMELHEM
Date: 22 June 2011
Date Type: Completion
Defense Date: 24 March 2011
Approval Date: 22 June 2011
Submission Date: 21 March 2011
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Computer Science
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Endurance modeling; wear-leveling
Other ID:, etd-03212011-194825
Date Deposited: 10 Nov 2011 19:32
Last Modified: 15 Nov 2016 13:37


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