Relative time in computer 2018-11-20 22:03

In this book Systems Performance: Enterprise and the Cloud author make a single CPU cycle equivalent to one second to make us feel how fast CPU is.

event Actual Latency Scaled Latency
One CPU cycle 0.3ns 1s
Level 1 cache access 0.9ns 3s
Level 2 cache access 2.8ns 9s
Level 3 cache access 12.9ns 43s
Main memory access (DDR DIMM) 120ns 6min
SSD I/O 50~150us 2~6days
Rotational disk I/O 1-10ms 1~12month
Internet call: San Francisco to New York City 40ms 4years
TCP packet retransmission 1~3s 105~317years
OS virtualization restart 40s 4,000years
Physical system restart 5m 32,000years