cache:

●technique used to improve access performance by accessing quick device than low-speed device.

1.use cache to improve memory access

2.use memory cache to improve disk access

●hit ratio 高低會影響 performance

●需考慮 data consistence的問題

buffering

●暫時性的儲存區域，通常用在例如 CPU 與 I/O operation 之 overlay execution 以提升 CPU 與 I/O utilization 降低 CPU 與 I/O idle time 或者資料的暫存，如 Keyboard buffer, I/O buffer 等。

●與 hit ratio 無關

●無需考慮，通常僅用 FIFO Queue 來 implement