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:material-circle-edit-outline: 约 95 个字

Measurements of Dependability

Module reliability: continuous service accomplishment ( of the time to failure )

• MTTF: Mean Time To Failure
  • 多久故障
• MTTR: Mean Time To Repair (service interruption)
  • 要修多久
• FIT: Failure In Time = 1/MTTF
  • 每单位时间累计的故障数
• MTBF: Mean Time Between Failure = MTTF+MTTR
  • 两次故障的间隔

$$ Module\;availability=\frac{MTTF}{MTTF+MTTR}=\frac{MTTF}{MTBF} $$ ​

Performance Metrics

• response time
  • 用户的角度
• CPU time
  • 系统的角度
• throughput
• MIPS

Amdahl’s Law

Calculation of CPU Time