CPUs and architecture

In a typical computer, which lists the memory hierarchy from fastest to slowest access?

  1. ASSD → main memory → L2 cache → L1 cache → registers
  2. BMain memory → registers → SSD → L1 cache
  3. CRegisters → L1 cache → L2 cache → main memory (DRAM) → SSD
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Answer: C. Registers → L1 cache → L2 cache → main memory (DRAM) → SSD

Memory closer to the CPU is faster and smaller; memory farther away is slower, larger and cheaper. A hierarchy of registers, L1/L2/L3 caches (SRAM), main memory (DRAM) and storage (SSD, etc.) keeps frequently used data in the faster levels, achieving memory that is fast and large overall.

Memory hierarchy of a computer Fast, small, expensive per bit Registers L1 cache L2/L3 cache Main memory (DRAM) Storage (SSD/HDD) Slow, large, cheap per bit
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More CPUs and architecture questions

  1. Approximately how many instructions per second can a processor with a 2 GHz clock and an average CPI (clocks per instruction) of 0.5 execute?
  2. If 90% of a program can be parallelized, what is the theoretical maximum speedup when it runs on an unlimited number of processors?
  3. Which scheme performs the same operation on multiple data items simultaneously with a single instruction?
  4. Which CPU configuration combines high-performance cores and power-efficient cores and uses them according to the workload?
  5. Which technique examines instruction dependencies and executes ready instructions in an order different from the program order to improve performance?