监控指标 TP99 TP999 含义

TP=Top Percentile,Top百分数,是一个统计学里的术语,与平均数、中位数都是一类。

TP50、TP90和TP99等指标常用于系统性能监控场景,指高于50%、90%、99%等百分线的情况。

首先给出Google到的答案:

The tp90 is a minimum time under which 90% of requests have been served.

tp90 = top percentile 90

Imagine you have response times:

10s
1000s
100s
2s

Calculating TP is very simple:

  1. Sort all times in ascending order: [2s, 10s, 100s, 1000s]
  2. find latest item in portion you need to calculate.
    2.1 For TP50 it will be ceil(40.5) = 2 requests. You need 2nd request. 2.2 For TP90 it will be ceil(40.9) = 4. You need 4th request.
  3. We get time for the item found above. TP50=10s. TP90=1000s

依此,翻译过来,TP99就是满足百分之九十九的网络请求所需要的最低耗时。同理TP999就是满足千分之九百九十九的网络请求所需要的最低耗时。

举个例子:有四次请求耗时分别为:

10ms,1000ms,100ms,2ms

那么我们可以这样计算TP99:4次请求中,99%的请求数为4*0.99,进位取整也就是4次,满足这全部4次请求的的最低耗时为1000ms,也就是TP99的答案是1000ms。

(可以认为 TP90的意思是保证90%请求都能被响应的最小耗时)

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