Performance: It’s not just CPU speed

CPU <–> Memory bandwidth can limit performance

  • Improving performance 1: hardware improvements to increase memory bandwidth (e.g., DDR -> DDR2 -> DDR3)
  • Improving performance 2: move less data into/out of the CPU (e.g., Put some “memory” in the CPU chip itself–this is “cache” memory)

The Hardware/Software Interface
July 2014

Intel® Core™ i5-2450M Processor (3M Cache)
Launch Date: Q1’12
Clock Speed 2.5 GHz
Instruction Set 64-bit
Max Memory Bandwidth 21.3 GB/s