指标

P99:
For example, a system might have a 99th percentile(also known as P99) lantency of 300ms;
this would mean that 99% of latencies are below 300ms;
A high-order percentile suc as P99 or even P99.9 can be used as a ballpark worst-case value

SLI: Service Level Indicator
大于 99.99%

https://www.sumologic.com/glossary/sli-service-level-indicator/