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KDAB
hotspot
C++2017–2025
KDAB / hotspot

hotspot

The Linux perf GUI for performance analysis.

Systems & InfrastructureMobile & DesktopTesting & Quality
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15Distinct people
16Mentions
0Explicit recommenders
5.2KGitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

The Linux perf GUI for performance analysis.

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

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This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:56:07 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year16 dated mentions

Observed mentions: 2017-09-29 12:47:10 UTC to 2025-06-20 16:20:09 UTC.

01232017-01-01 00:00:00 UTC to 2018-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments20172018-01-01 00:00:00 UTC to 2019-01-01 00:00:00 UTC (exclusive): 2 mentions; 1 submissions, 1 comments2019-01-01 00:00:00 UTC to 2020-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2020-01-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-01-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments20212022-01-01 00:00:00 UTC to 2023-01-01 00:00:00 UTC (exclusive): 3 mentions; 0 submissions, 3 comments2023-01-01 00:00:00 UTC to 2024-01-01 00:00:00 UTC (exclusive): 2 mentions; 1 submissions, 1 comments2024-01-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 3 mentions; 0 submissions, 3 comments2025-01-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 3 mentions; 1 submissions, 2 comments2025

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20172017-01-01 00:00:00 UTC2018-01-01 00:00:00 UTC101
20182018-01-01 00:00:00 UTC2019-01-01 00:00:00 UTC211
20192019-01-01 00:00:00 UTC2020-01-01 00:00:00 UTC101
20202020-01-01 00:00:00 UTC2021-01-01 00:00:00 UTC000
20212021-01-01 00:00:00 UTC2022-01-01 00:00:00 UTC101
20222022-01-01 00:00:00 UTC2023-01-01 00:00:00 UTC303
20232023-01-01 00:00:00 UTC2024-01-01 00:00:00 UTC211
20242024-01-01 00:00:00 UTC2025-01-01 00:00:00 UTC303
20252025-01-01 00:00:00 UTC2026-01-01 00:00:00 UTC312

What Hacker News says

16 sources
badsectoracula·Jun 20, 2025
> I suspect that I have an outdated version of hotspot Linux profiler, but I can’t just go and download a fresh release from GitHub, because hotspot is a KDE app, and I use NixOS. KDE (not to be confused with the Plasma desktop) is just a bunch of C++ libraries that can work on a variety of desktop environments and even OSes (though Hotspot being a perf report alternative is clearly meant for use with Linux). I just went and downloaded the latest CI build from[0] and it ran just fine on my openSUSE Tumbleweed, running Xorg with Window Maker. I do have a bunch of KDE apps installed, like Kate (my currently preferred text editor), Dolphin (the file manager i use whenever i want thumbnails, usually for videos and images), Spectacle (for screenshots), Falkon (i use it as a "clean" browser to test out things), etc so i also do have the KDE lib
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raries on my system, but that is just a `zypper install` away. Or an `apt-get install` or `pacman -S` or whatever package manager your distro uses, i've used a bunch of them and they all pretty much behaved the same. I'd expect Hotspot to be installable in the same way in any of them (and i'd expect the AppImage to have these libraries bundled in anyway so you probably wont need them[1]). If there are issues with NixOS (i don't know, i haven't tried it) i think it might actually be a NixOS issue and not a KDE issue. [0] https://github.com/KDAB/hotspot/releases/tag/continuous [1] EDIT: i checked with --appimage-extract, it contains pretty much everything
In Open source can't coordinate?
lelanthran·Sep 3, 2024
> The premise of this website and articles like https://yosefk.com/blog/how-profilers-lie-the-cases-of-gprof... just show that the authors are using the wrong tools. It is nowadays relatively easy to also look at off-CPU time when profiling with perf (e.g. https://github.com/KDAB/hotspot/?tab=readme-ov-file#off-cpu-...). I think, firstly, that spending 15s trying the CTRL-c approach is a worthwhile tradeoff. If you don't find anything, then sure, spend another 30m - 60m setting up perf, KDAB, etc. Maybe more if you're on an embedded device. Secondly, the author seems to say that he's used this on embedded devices with no output but a serial line for the debugger. This is also a 15s effort[1]. It's basically a very low effort task, takes seconds to determine if it worked or not, and if it doesn't work you've only lost a few seconds. [1] I'
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m assuming that if you're developing on a device supporting a serial GDB connection, you've already got the debugger working.
In Profiling with Ctrl-C
milianw·Sep 3, 2024
The premise of this website and articles like https://yosefk.com/blog/how-profilers-lie-the-cases-of-gprof... just show that the authors are using the wrong tools. It is nowadays relatively easy to also look at off-CPU time when profiling with perf (e.g. https://github.com/KDAB/hotspot/?tab=readme-ov-file#off-cpu-...). The idea is to use sampling for the on-CPU periods and then combine that with the off-CPU time measured between context switches. VTune also supported this mode for many years.
In Profiling with Ctrl-C
themulticaster·Mar 1, 2023
I'm not familiar with how it compares to ARM/Intel's profiling tools, but I found the Linux perf suite to be very capable (though limited to Linux obviously). And Hotspot [1] allows effortless profile visualization using flame graphs, including some very interesting features such as off-CPU time profiling [2]. "perf record" coupled with Hotspot forms a very smooth edit-compile-profile cycle. [1] https://github.com/KDAB/hotspot [2] https://github.com/KDAB/hotspot#off-cpu-profiling
In “Clean” code, horrible performance
themulticaster·Jul 27, 2022
If I understand correctly valgrind (cachegrind) reports L1/L2 cache misses based on a simulated CPU/cache model. On Linux, you can easily instrument real cache events using the very powerful perf suite. There is an overwhelming number of events you can instrument (use perf-list(1) to show them), but a simple example could look like this: $ perf stat -d -- sh -c 'find ~ -type f -print | wc -l' ^Csh: Interrupt Performance counter stats for 'sh -c find ~ -type f -print | wc -l': 47,91 msec task-clock # 0,020 CPUs utilized 599 context-switches # 12,502 K/sec 81 cpu-migrations # 1,691 K/sec 569 page-faults # 11,876 K/sec 185.814.947 cycles # 3,878 GHz
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(28,71%) 105.650.405 instructions # 0,57 insn per cycle (46,15%) 22.991.322 branches # 479,863 M/sec (46,72%) 643.767 branch-misses # 2,80% of all branches (46,14%) 26.010.223 L1-dcache-loads # 542,871 M/sec (36,80%) 2.449.173 L1-dcache-load-misses # 9,42% of all L1-dcache accesses (29,62%) 517.052 LLC-loads # 10,792 M/sec (22,53%) 133.152 LLC-load-misses # 25,75% of all LL-cache accesses (16,02%) 2,403975646 seconds time elapsed 0,005972000 seconds user 0,046268000 seconds sys 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.
In Twenty years of Valgrind
bd6a28·Mar 19, 2022
> [...] 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
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hotspot [3] for flame graphs or HPerf [4] 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/
In Linux Perf Examples
jrockway·May 11, 2021
Thought it might also be helpful to add that I usually invoke perf like this: perf record --call-graph dwarf -e cycles --switch-events --sample-cpu -p $(pidof my-go-process) And then view the results in hotspot (https://github.com/KDAB/hotspot). I played a little with off-cpu profiling (-e sched:sched_switch), but Go kind of outsmarts that by doing its own scheduling (taking Goroutines off Machines when it thinks it's going to block inside a syscall, so the resulting flamegraphs are usually rooted in runtime.park_m; though if the runtime gets something wrong, you'd be able to see it here.)
In Pprof++: A Go Profiler with Hardware Performance Monitoring

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