Calculate extra latency allowed in routing layer

Overview

For us to route the user to the right Cell we need to check which Cell the route belongs too. There are some proposals at the moment:

• Buffering Requests
• Route learning
• Published Route Filters

All these will require the router to contact a Cell to get the information and cache that information which means we are going to add latency to every request since there is an extra network hop.

Action Items

• Get p99, p95, p90, p50 for web, git and api with calculated headroom
  • web 👉 #432934 (comment 1667993089)
  • git 👉 #432934 (comment 1671385680)
  • api 👉 #432934 (comment 1669995479)
• Get request latency from client perspective 👉 #432934 (comment 1671631440)
• Get request latency from loadbalancer
  • cross regional 👉 #432934 (comment 1671654914)
  • Loadbalancer RTT 👉 #432934 (comment 1671701611)
• Write findings in a blueprint for routing requirements 👉 !138297 (merged)