What do we mean by "top percentile" or TP based latency?

StackOverflow https://stackoverflow.com/questions/17435438

Question

When we discuss performance of a distributed system we use the terms tp50, tp90, tp99.99 TPS. Could someone explain what do we mean by those?

Was it helpful?

Solution

tp90 is a maximum time under which 90% of requests have been served. Imagine you have times:

10s
1000s
100s
2s

Calculating TP is very simple:

  • sort all times in ascending order: [2s, 10s, 100s, 1000s]
  • find latest item in portion you need to calculate. For TP50 it will ceil(4*.5)=2 requests. You need 2nd request. For TP90 it will be ceil(4*.9)=4. You need 4th request.
  • get time for the item found above. TP50=10s. TP90=1000s

OTHER TIPS

Say if we are referring to in-terms of performance of an API, TP90 is the max time under which 90% of requests have been served.

TPx: Max response time taken by xth percentile of requests.

time taken by 10 requests in ms [2,1,3,4,5,6,7,8,9,10] - there are 10 response times

TP100 = 10   
TP90 = 9   
TP50 = 5
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