Review5.1 | Memory Hierarchy Basic

:material-circle-edit-outline: 约 148 个字

上面这个rotational latency怎么计算？

Programs access a small proportion of their address space at any time

• Temporal locality: Items accessed recently are likely to be accessed again soon
• Spatial locality: Items near those accessed recently are likely to be accessed soon

Memory Hierarchy Levels

• Hit time:
  • The time to access the upper level of the memory hierarchy,
  • which includes the time needed to determine whether the access is a hit or a miss.
    • access time + check hit/miss time
• miss penalty
  • The time to replace a block in the upper level with the corresponding block from the lower level,
  • plus the time to deliver this block to the processor.
    • replace time + access time

• Miss ratio + hit ratio = 1

hit定义是，CPU读取 层级最近的mem 是否直接成功

Memory system