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"Performance Matters" by Emery Berger

Strange Loop Conference · talk · Watch on YouTube

Software performance & optimizationTesting, debugging & developer tools

What it is

Emery Berger explains why performance is hard to measure and deliver on modern hardware, showing how code layout and alignment can swamp optimization effects. He presents Stabilizer for statistically sound evaluation and Coz, a causal profiler.

Why Hacker News recommends it

It is the standard recommendation for anyone puzzled by unexplained benchmark changes from tiny code edits, and for learning about causal profiling.

  • 12 people recommended it
  • 10 different months
  • 5 strong recommendations
  • first 2019, last 2025

What HN commenters said

  1. “is a great talk”

    Great Strange Loop talk on performance

    divan, 2019-12 · Strong recommendation · in “Ask HN: Best Talks of 2019?”

  2. “which I highly recommend. Lots of really nice insight, even outside of this tool.”

    Insight on causal profiling and performance optimization

    jaybosamiya, 2020-01 · Strong recommendation · in “Measure code execution time accurately in Python”

  3. “this is the most amazing optimisation information I have seen”

    Hidden CPU performance variation and causal profiling finding speedups in SQLite

    robocat, 2020-05 · Strong recommendation · in “The naked truth about writing a programming language (2014)”

  4. “I would highly recommend Emery Berger's talks [1] for anyone interested in benchmarking software.”

    Code layout and alignment have large performance effects on benchmarks

    acidbaseextract, 2020-12 · Strong recommendation · in “Ryzen 5800X vs. M1: Programming benchmarks”

  5. “Emery Berger has an excelent talk on this [1]”

    Memory layout dominates benchmarks; people over-trust noisy statistics

    j-pb, 2023-06 · Strong recommendation · in “Poop: Performance Optimizer Observation Platform”

  6. “does a good job discussing the impact of alignment and other 'small' changes on performance”

    Discusses how alignment and small changes affect performance and estimating impact

    kristjansson, 2020-06 · Recommendation · in “C performance mystery: delete unused string constant”

  7. “I'd encourage watching this talk”

    Relevant to unexplained performance changes from small code edits

    Twirrim, 2020-06 · Recommendation · in “C performance mystery: delete unused string constant”

  8. “Try getting them to watch this talk by Emery Berger”

    Talk to show colleagues, introducing the Coz profiler

    vanderZwan, 2021-04 · Recommendation · in “Prefix Trees in Action”

Excerpts from Hacker News comments, linked to the originals. Summaries and labels were written by a language model from those comments.

Topics: causal profiling, coz, benchmarking, memory layout, emery berger, optimization

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