Superconducting Technology Assessment - nitrd

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SYSTEM ARCHITECTURES System-level Hardware Architecture The primary challenges to achieving extremes in high performance computing are 1) integrating sufficient hardware to provide the necessary peak capabilities in operation performance, memory and storage capacity, and communications and I/O bandwidth, and 2) devising an architecture with support mechanisms to deliver efficient operation across a wide range of applications. For peta-scale systems, size, complexity, and power consumption become dominant constraints to delivering peak capabilities. Such systems also demand means of overcoming the sources of performance degradation and efficiency reduction including latency, overhead, contention, and starvation. Today, some of the largest parallel systems routinely experience floating point efficiency of below 10% for many applications and single digit efficiencies have been observed, even after efforts towards optimization. The “obvious” approach for deploying RSFQ in a high-end computer is to replicate a traditional MIMD (multiple instruction, multiple data) architecture. Processing nodes (processors and memory) are interconnected with a high-speed network: Node (processor/ memory) Node (processor/ memory) Node (processor/ memory) Node (processor/ memory) High speed interprocessor network I/O node I/O node I/O node Storage Unfortunately, physical realities intervene and such a system would be unbalanced: it would have very high speed processing and high latency inter-processor communications. In addition, the differential between storage access latencies and processor speed would very high, on the order of 10 6 -10 9 . It would also require large amounts of memory per node (the rule of thumb usually applied is 1 byte/FLOPS); this in turn increases the physical size and thus the inter-node communications delays. This architecture supports compute-intensive applications, but would perform poorly for data-intensive applications. Indeed, considerable time would be wasted in loading memory from disk. Most supercomputing applications have a mix of compute-intensive and data-intensive operations; a different approach to architecture is needed. 161
Only one significant effort to architect a balanced supercomputer architecture that could effectively incorporate RSFQ has been carried out to date. In the initial HTMT study, Sterling, Gao, Likharev, and Messina recognized that RSFQ provided the blinding processing speed desired for compute-intensive operation, while CMOS was needed to provide the high-density, low-cost components needed for data-intensive operation and access to conventional I/O and storage devices. This led to a three-tier processing architecture with two communications layers: High - speed network for RSFQ interprocessor communications RSFQ node RSFQ node RSFQ node RSFQ node 4º K Staging electronics Staging electronics Staging electronics Staging electronics Interprocessor network for data intensive operations CMOS node CMOS node CMOS node CMOS node CMOS node CMOS node CMOS node CMOS node CMOS node CMOS node CMOS node 25º C Not shown are the attached storage and I/O devices. These would be connected to CMOS nodes or to the data-intensive network and would achieve high aggregate bandwidth as a result of parallel access. A closer look at memory technologies led to inclusion of a layer of “bulk” memory—high-density, block-access memory such as might be provided by holographic storage or disk. Even with the high feature densities achieved by CMOS, a petabyte of memory takes up significant space. (Note that partitioning the architecture into distinct compute-intensive and data-intensive segments correlates with the two operating temperature regimes. We found this useful in defining technology boundaries for this study.) The HTMT project identified and pursued several technologies that might efficiently implement a design based on the above conceptual architecture. At its conclusion, the HTMT architecture had taken the form concurrently. In practice, there are limits to the degree of concurrency supportable by a given application at any one time. Low latency is desirable, but latency is limited by speed-of-light considerations, so the larger the system, the higher the latency between randomly selected nodes. As a result, applications must be capable of high degrees of parallelism to take advantage of physically large systems. 162
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SUPERCONDUCTING TECHNOLOGY ASSESSME
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Summary of Findings The STA conclud
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CHAPTER 02: ARCHITECTURAL CONSIDERA
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CHAPTER 06: SYSTEM INTEGRATION 6.1
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INDEX OF FIGURES CHAPTER 01: INTROD
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APPENDIX G: ISSUES AFFECTING RSFQ C
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CONTENTS OF CD EXECUTIVE SUMMARY CH
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LIMITATIONS OF CURRENT TECHNOLOGY C
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State of the Industry Today, expert
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01 This document presents the resul
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1.2 LIMITATIONS OF CONVENTIONAL TEC
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1.3.2 RSFQ ATTRIBUTES Important att
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The end point of this roadmap defin
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CRYOGENIC ENVIRONMENT High-speed ne
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■ ■ Chalmers University in Swed
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Random Access Memory Options Random
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Compact Package Feasible Thousands
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The major issue to be addressed wil
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02 No radical execution paradigm sh
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The key challenges at the processor
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2.2 MICROPROCESSORS - CURRENT STATU
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2.2.3 CORE1 BIT-SERIAL MICROPROCESS
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Potential Problems The initial vers
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The microarchitecture of supercondu
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2.5 MICROPROCESSORS - CONCLUSIONS A
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2.7 MICROPROCESSORS - FUNDING In th
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SUPERCONDUCTIVE RSFQ PROCESSOR AND
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3.1 RSFQ PROCESSORS The panel devel
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TABLE 3.1-1. PUBLISHED SUPERCONDUCT
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S G G Chip-side microstrip S Carrie
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3.1.3 RSFQ PROCESSORS - ROADMAP The
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3.1.5 RSFQ PROCESSORS - ISSUES AND
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Since these memory concepts are so
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Simulations show that the input int
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SFQ RAM Status The results of five
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Investment for SFQ Memory The inves
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4MB MRAM BIT CELL: 1 MTJ & 1 TRANSL
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The roadmap identifies early analyt
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MRAM Major Issues and Concerns Mate
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3.3 CAD TOOLS AND DESIGN METHODOLOG
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Issues and Concerns Present simulat
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Investment The investment estimated
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04 By 2010 production capability fo
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Table 4-1 summarizes the roadmap fo
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4.1 SCE IC CHIP MANUFACTURING - SCO
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Significant activity in the area of
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4.3 SCE CHIP FABRICATION FOR HEC -
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The superconductive IC chip fabrica
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Table 4-6 shows how gate speed depe
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Parameter spreads in superconductiv
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TABLE 4-9. SCALING REQUIREMENTS FOR
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ELEMENT 2006 2007 2008 2009 2010 Pi
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A potential savings of ~40% in the
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05 Packaging and chip-to-chip inter
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TABLE 5-1. I/O TECHNOLOGIES FOR PET
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For further discussions of the opti
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5.1.3 OPTICAL INTERCONNECT TECHNOLO
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In this case, an optical receiver w
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Examples of what has been achieved
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5.3.4 OUTPUT: 4 K RSFQ TO ROOM TEMP
Page 123 and 124: Figure 5-4. Superconducting 16x16 c
Page 125 and 126: 06 The design of secondary packagin
Page 127 and 128: For this study, the readiness of th
Page 129 and 130: 6.1.3 MULTI-CHIP MODULES AND BOARDS
Page 131 and 132: TABLE 6-2. MCM FABRICATION TOOLS AN
Page 133 and 134: 6.2.3. 3-D PACKAGING - ISSUES AND C
Page 135 and 136: Several companies have demonstrated
Page 137 and 138: In selecting the cooling approach f
Page 139 and 140: Another issue is the cost of the re
Page 141 and 142: Some of the thermal and electrical
Page 143 and 144: Optical interconnects may require t
Page 145 and 146: 6.6.4 SYSTEM INTEGRITY AND TESTING
Page 147 and 148: Appendix A
Page 149 and 150: ■ ■ ■ ■ Construct a detaile
Page 151 and 152: Appendix B
Page 153 and 154: GOVERNMENT George Cotter Director f
Page 155 and 156: Appendix C
Page 157 and 158: TERMS/DEFINITIONS IHEC LLNL JJ JPL
Page 159 and 160: Appendix D
Page 161 and 162: The time-dependent behavior of this
Page 163 and 164: RSFQ electronics is faster and diss
Page 165 and 166: Similar to CMOS, the irreducible po
Page 167 and 168: Appendix E
Page 169 and 170: The report further identified four
Page 171 and 172: Analog high temperature superconduc
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Page 177 and 178: Execution Models Organizing hardwar
Page 179 and 180: Development Issues and Approaches T
Page 181 and 182: Appendix G
Page 183 and 184: The two-junction comparator, the ba
Page 185 and 186: Bias Currents A major cause of degr
Page 187 and 188: Power and bias current Power is dis
Page 189 and 190: Appendix H
Page 191 and 192: SMT MRAM Another direct selection s
Page 193 and 194: Speed and Density The first planned
Page 195 and 196: 120 0.10 100 Write I (mA) 0.08 0.06
Page 197 and 198: Appendix I
Page 199 and 200: Table 1 Representative Nb and NbN-B
Page 201 and 202: ground plane may be located either
Page 203 and 204: Table 5 Reactive Ion Etch Parameter
Page 205 and 206: Table 6 Junction Array Summary of T
Page 207 and 208: shorts in the first wiring layer we
Page 209 and 210: B. Yield Yield measurements are an
Page 211 and 212: RSFQ logic will eventually find wid
Page 213 and 214: [47] B. Bumble, H. G. LeDuc, J. A.
Page 215 and 216: Appendix J
Page 217 and 218: Fig. 2. The Schematic View describe
Page 219 and 220: Fig. 4. The VHDL View captures the
Page 221 and 222: Fig. 6. LMeter is specialized softw
Page 223 and 224: Fig. 8. Layout-versus-Schematic ver
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Appendix K
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1. CURRENT STATUS OF OPTICAL INTERC
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1.2. CURRENT OPTICAL INTERCONNECT R
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If technology, power, or cost limit
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3.4 COARSE VS. DENSE WAVE DIVISION
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3.5 DEVELOPMENTS FOR LOW TEMPERATUR
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5. ROADMAP The roadmap below shows
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Appendix L
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The bandwidth, chip density and int
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While using short flex cables is th
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We must note that the reparability
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Intermediate Temperature stage Disp
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Small Cryocoolers Among commercial
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Although cooling of the 4 K circuit
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Supplying DC current to all of the
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These properties enable the possibi
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