hotspot
FlameGraph
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hotspot | FlameGraph | |
---|---|---|
16 | 53 | |
3,847 | 16,406 | |
2.1% | - | |
9.3 | 4.9 | |
7 days ago | 8 days ago | |
C++ | Perl | |
GNU General Public License v3.0 or later | - |
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hotspot
- Hotspot: A GUI for the Linux perf profiler
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What is your favourite profiling tool for C++?
perf with Hotspot 👌
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Profiling C code on an M1 mac
If you’re able to use perf on Linux, I would recommend hotspot for visualizing the results.
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What is the problem with transfer speeds withing Dolphin?
I can recommend you using the https://github.com/KDAB/hotspot/ tool whenever you want to study performance.
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Data-driven performance optimization with Rust and Miri
Every Linux C/C++/Rust developer should know about https://github.com/KDAB/hotspot. It's convenient and fast. I use it for Rust all the time, and it provides all of these features on the back of regular old `perf`.
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How to interpret a flamegraph?
Flamegraphs alone aren't a full picture of what your application is doing, but it can give you hints as to where to look. Another tool I often use is Hotspot which can open the perf.data file and provide more options for filtering and digging into the gathered data beyond the single flamegraph.
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Twenty Years of Valgrind
Ignore the command, it's just a placeholder to get meaningful values. The -d flag adds basic cache events, by adding another -d you also get load and load miss events for the dTLB, iTLB and L1i cache.
But as mentioned, you can instrument any event supported by your system. Including very obscure events such as uops_executed.cycles_ge_2_uops_exec (Cycles where at least 2 uops were executed per-thread) or frontend_retired.latency_ge_2_bubbles_ge_2 (Retired instructions that are fetched after an interval where the front-end had at least 2 bubble-slots for a period of 2 cycles which was not interrupted by a back-end stall).
You can also record data using perf-record(1) and inspect them using perf-report(1) or - my personal favorite - the Hotspot tool (https://github.com/KDAB/hotspot).
Sorry for hijacking the discussion a little, but I think perf is an awesome little tool and not as widely known as it should be. IMO, when using it as a profiler (perf-record), it is vastly superior to any language-specific built-in profiler. Unfortunately some languages (such as Python or Haskell) are not a good fit for profiling using perf instrumentation as their stack frame model does not quite map to the C model.
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Linux Perf Examples
> [...] how Perf compares to vendor tools like vTune [...] ?
Regarding the hardware events that Perf can capture on x86, it has pretty much all of them. So it should be equivalent to vTune for all practical purposes.
The big difference is in the UI -- or absence thereof. Perf is a low-level tool and its output is mostly text files. There is a curses-based TUI for perf-report (and even gtk version, but it is essentially the same as the TUI, just using GTK2 widgets), but that's about it.
By contrast, vTune comes with a heavy (electron-based?) GUI and is quite helpful in guiding beginners, with many graphs and explanations.
Of course, one can (and is expected to) complement Perf with an assortment of tools that process its output for visualization. For example, the flamegraph [1] and heat map [2] tools described in the article. But also KDAB hotspot [3] or HPerf for a vTune-style perf-report.
[1] https://github.com/brendangregg/FlameGraph
[2] https://github.com/brendangregg/HeatMap
[3] https://github.com/KDAB/hotspot
[4] https://www.poirrier.ca/hperf/
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Parsers that don't yet exist?
https://github.com/KDAB/hotspot might contain parsing code you could use as an example (other than perf script). It always accepts raw perf.data, and there doesn't seem to be a way to feed it the output of perf script, so it might be parsing it directly instead of calling perf script.
FlameGraph
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JVM Profiling in Action
We'll use async-profiler and flame graphs for profiling. To simplify the process, we'll run the code using JBang.
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Memray – A Memory Profiler for Python
And flame graphs excel and this kind of thing
https://www.brendangregg.com/flamegraphs.html
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All my favorite tracing tools: eBPF, QEMU, Perfetto, new ones I built and more
which can output in a format understood by Brendan Gregg's flame frames (https://www.brendangregg.com/flamegraphs.html)
But that's not quite the kind of tracing you're talking about. We also built a printf-style interface to our recording files, which seems closer:
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Recap of Werner Vogels' Keynote at re:Invent 2023
Strategies included discontinuing or resizing underutilized services, transitioning to more cost-effective solutions, reducing the current resources to the amount of resources that we need for our application, and conducting detailed analyses of computing resource utilization through tools like flamegraphs. This detailed scrutiny helped identify and rectify significant cost-driving areas, such as garbage collection and application configurations.
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Pinpoint performance regressions with CI-Integrated differential profiling
Flame Graphs by Brendan Gregg
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Flameshow: A Terminal Flamegraph Viewer
Historically brendangregg's since AIUI he basically invented flamegraphs
https://www.brendangregg.com/flamegraphs.html
So if you can make your tool eat whatever https://github.com/brendangregg/FlameGraph is fed with you're going to support a lot of existing tooling across OSes and languages.
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Introducing Flame graphs: It’s getting hot in here
“Flame graphs are a visualization of hierarchical data, created to visualize stack traces of profiled software so that the most frequent code-paths to be identified quickly and accurately.”
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Using SVG to create simple sparkline charts
SVGs are amazing for interactive visualisation too. Like Flamegraphs: https://www.brendangregg.com/flamegraphs.html
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Good example of using flame graphs to speed up java code (50x improvement)
This may be a good example of the application of a flame graph but it is not a good demonstration of flame graphs; the graph is nearly incidental. The source has an actual explanation.
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Intro to PostGraphile V5 (Part 1): Replacing the Foundations
A profiling flame graph from Graphile Crystal (a precursor to Grafast) using GraphQL.js' executor (each tick is 1ms, total: 29ms). As we removed more and more responsibilities from GraphQL.js, we ended up only using it for output. Replacing this final responsibility with a custom implementation in Graphile Crystal itself, we reduced execution time for this query down to 15.5ms (effectively removing the majority of the yellow portion of the flame graph).
What are some alternatives?
polkit-dumb-agent - a polkit agent in 145 lines of code, because polkit is dumb and none of the other agents worked
benchmark - A microbenchmark support library
firestorm - A fast intrusive flamegraph
tracing-bunyan-formatter - A Layer implementation for tokio-rs/tracing providing Bunyan formatting for events and spans.
gta5view - Open Source Snapmatic and Savegame viewer/editor for GTA V
HeatMap - Heat map generation tools
cargo-flamegraph - Easy flamegraphs for Rust projects and everything else, without Perl or pipes <3
node-clinic - Clinic.js diagnoses your Node.js performance issues
optick-rs - Optick for Rust
pmu-tools - Intel PMU profiling tools
Viper-Browser - A lightweight Qt5 web browser using QtWebEngine
etcd - Distributed reliable key-value store for the most critical data of a distributed system