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CSE 691: Energy-Efficient ComputingLecture 7
SMARTS: custom-made systemsAnshul Gandhi
1307, CS [email protected]
memcache
Benchmark competitions
Benchmark competitions
fawn paper
Data-intensive workloads
Seek-bound• small• random
• examples?• problems?
Scan-bound• large• sequential
• examples?• problems?
Why FAWN?
1. Memory wall (??)
2. Increased CPU power consumption
3. DVFS is limited
• Modern CPUs operate close to Vmin
• Constant leakage current
4. Peak power and data center density
FAWN results
Processor scaling trends
1. Moore’s law (observation)• # transistors/chip ↑ 2X/2yr (how?)• Frequency ↑ as transistor size ↓ (max 9GHz)
• Leakage current/power ↑ as transistor size ↓• Heat ↑ as frequency ↑
Processor scaling trends
2. Dennard scaling (observation)• Transistor power (V+I) ↓ as transistor size ↓• + Moore’s law = perf/watt ↑ 2X/2yr (how?)
• Not true now due to leakage current
• So we did multicore!
heteromates paper
Dark silicon
• Cannot power on all of the CPU• Result of:
1. Success of Moore’s law2. Failure of Dennard scaling
• Turbo boost
Main ideas
• Heterogeneous cores1. For different performance requirements2. Energy considerations (battery vs. plugged)3. Thermal considerations4. Dark silicon
Main ideas
Main ideas