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What are embedded systems?
1- Low power2- Fast (critical throughput) 3- Particular task4- Reliable5- Cheap6- Small size
Applications:
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Platforms:
Microcontrollers Microprocessors FPGA Digital signal processors Application specific integrated circuits
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Power consumption reduction
Power is influenced by voltage andpulses on each part of hardware
Traditional idea:Reducing voltage and frequency if necessary
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Power consumption reduction
New ideareducing hardware to obtain the least states between instructions, data and functional units.
Instruction>>Pipeline, branch prediction, memory access, speculation and etc.>>function unit
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worst-case of execution time
Pipeline (hazards and stages)SpeculationeventsBranch miss predictionCache miss
Computing maximum band of execution time:Exclude as many possible timing accident
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Cache
The most important consideration for cache speedup is predictability.
May: upper approximations of cache contentMust: lower approximations of cache contentEvict: when “may” information becomes availableFill: when “must” and “may” information is obtained
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Multicores
Not highly recommended Avoiding shared resources conflict Using crossbars for communication
between shared resources Private L1 and L2 replacement
strategies
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Conclusion
Simplifying the hardware causes increasing in critical throughput and power saving
We must take care of these simplicities
Software must carry the burden of simplicity in hardware.