DRAM and Memory System Trends - IBM Research

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Addressing Memory Latency “Bandwidth problems can be cured with money. Latency problems are harder because the speed of light is fixed – you can’t bribe God.” -- Anonymous • Physical distances remaining roughly fixed • Electrical distance increases as CPU clock speeds increase • Reducing DRAM access latency comes at a price • Increasing storage cell capacitance reduces latency… • …but increases storage cell area, reducing storage capacity • DRAMs must provide high density, inexpensive storage DRAMs must balance access latency and storage density ISMM 2004 Keynote
Integration of Mem Controller Into CPU Offers Large Latency Reduction • Latency between CPU and mem controller eliminated • Memory controller runs at CPU clock speed • Shifts decision on memory type forward in design cycle • Benefit is large -- AMD, Compaq, others integrating memory controllers into CPU CPU Front Side Bus Memory Controller Memory Bus Memory ISMM 2004 Keynote
Page 1 and 2: DRAM and Memory System Trends Steve
Page 3 and 4: Amdahl’s Law and The Processor- M
Page 5 and 6: What Makes A Good Memory System? Hi
Page 7 and 8: Memory Latency Trends CPU 1990 2004
Page 9: Addressing Memory Latency “Bandwi
Page 13 and 14: Rising Front Side Bus Speeds Fuel t
Page 15 and 16: Physical Constraints Increase Per-p
Page 17 and 18: Signaling Speed Limited by Capacita
Page 19 and 20: Reflections Limit Signal Integrity
Page 27 and 28: Signal Quality at DRAM Changes With
Page 29 and 30: Signal Quality at DRAM Changes With
Page 31 and 32: Signal Integrity Issues Limiting Si
Page 33 and 34: Improving Signal Integrity With On-
Page 39 and 40: Coming to a Server Near You: The Ad
Page 41 and 42: Memory Latency and Bandwidth are no
Page 43 and 44: Why Memory Systems Need More Banks
Page 45 and 46: Memory System Trends and Issues •
Page 47 and 48: Cost Reduction Critical in Some Con
Page 49 and 50: Reduced Power Consumption Critical
Page 51 and 52: Signaling Rates Limited by Signalin
Page 53 and 54: Equalization Enables Even Higher Si
Page 55: Summary • Latency continues to be

DRAM and Memory System Trends - IBM Research

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