# perf

13 Hacker News commenters recommended perf and 4 criticized it, November 2025 to November 2026. It was recommended in 8 of 13 months. It meets the Hacker Approved badge rule.

**Verdict:** Free Linux profiler that people rely on to find where code spends its time, and to build intuition for CPU performance. Its output is raw, and it expects you to already understand the OS.

## Why people recommend it

- Go-to tool for profiling (3 comments): "You can always go through cachegrind or perf and see what happens with your code." ([source](https://news.ycombinator.com/item?id=47806272)) "that's the best tool for my jobs" ([source](https://news.ycombinator.com/item?id=49416681)) "You can also just use perf" ([source](https://news.ycombinator.com/item?id=46202946))
- Simple to use, gets far (2 comments): "Perf, instruments and UIForETW are simple enough to use that anyone who can follow the instructions" ([source](https://news.ycombinator.com/item?id=46479493)) "perf record + perf report will get you pretty far on Linux" ([source](https://news.ycombinator.com/item?id=47655077))
- Builds intuition for CPU performance (2 comments): "Using perf on Linux has been very educational for me to get an intuition for modern CPU performance." ([source](https://news.ycombinator.com/item?id=49052631)) "Getting familiar with linux's perf tool is also helpful" ([source](https://news.ycombinator.com/item?id=46225751))

## What people warn about

- Assumes you know the OS (2 comments): "perf assumes you know how the OS works, and what various syscalls are doing." ([source](https://news.ycombinator.com/item?id=46935890)) "it's not optimized for reality because that knowledge can't be assumed" ([source](https://news.ycombinator.com/item?id=46937271))

## Alternatives hackers recommend

- [Java Flight Recorder](https://hackerapproved.com/p/java-flight-recorder.md): 10 recommend
- [Instruments](https://hackerapproved.com/p/instruments.md): 9 recommend
- [Perfetto](https://hackerapproved.com/p/perfetto.md): 8 recommend
- [Python 3.15 sampling profiler](https://hackerapproved.com/p/python-3-15-sampling-profiler.md): 6 recommend
- [Heaptrack](https://hackerapproved.com/p/heaptrack.md): 5 recommend

## Cite as

Hacker Approved, "perf", https://hackerapproved.com/p/perf/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).