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"How NOT to Measure Latency" by Gil Tene

Strange Loop Conference · 119.2K views · 2015-09-28 · 42:59

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Overview

Gil Tene of Azul Systems explains common pitfalls in measuring latency and response time, including why averages mislead and the problem of coordinated omission. He introduces open source tools like HdrHistogram for better measurement and reporting.

On Hacker News

The canonical recommendation whenever percentiles, tail latency, load testing or averages come up, described by some as life changing.

Recommended by 9 HN people across 9 months · HN mentions 2015–2026

Topics

Software performance & optimizationTesting, debugging & developer tools
Search by tags
coordinated omissionpercentilestail latencyhdrhistogramperformance testing

What people said

leetrout · 2023-05 · Strong recommendation

We use locust at work but I HIGHLY recommend wrk for a very robust yet simple load testing tool. [LINK] And of course, this talk by Gil Tene is fantastic if you're interested in load testing stats [VIDEO]

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wmfiv · 2020-04 · Strong recommendation

This a life changing video by Gil Tene on this topic. Bottom line is because of the number requests to support a single customer "request", the high percentiles are the ones that actually matter. [VIDEO]

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Rafuino · 2019-04 · Strong recommendation

This topic always leads me to think about this great talk from Gil Tene on how NOT to measure latencies (basically, don't use averages!). [VIDEO] I'm also a huge fan of how Dormando showed latency distributions in one of his recent Memcached Extstore posts. The default is 95th percentile but you can change the percentile to what matters to you (i.e. 99th percentile if you ask me!). Scroll down to see what he did and play with it. [LINK]

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Sources

Video by Strange Loop Conference, played through YouTube.

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