← recall

tail latency term

the slow end of the request distribution (p99/p999)

Most requests are fast, but a small percentage are dramatically slower. p99 is your 99th percentile — 1 in 100 requests is at least this slow. Tail latency dominates user experience at scale.

aliases: p99, long tail, high percentile latency

topics: latency, metrics

references:

• The Tail at Scale (Dean & Barroso)
• Gil Tene — How NOT to Measure Latency