Monday, 3 August 2026
… is now hosted on KDE infrastructure, instead of this blog! Check out the July 2026 post, or the entire series here.
… is now hosted on KDE infrastructure, instead of this blog! Check out the July 2026 post, or the entire series here.
Welcome to the inaugural edition of This Month in KDE Linux hosted on blogs.kde.org!
Previously, these posts lived on Nate Graham’s personal blog. But KDE Linux is growing up and becoming a more important part of KDE, larger than its individual contributors! So it’s time to move the public communication to KDE infrastructure, and that’s where you’ll be able to read these posts going forward.
Without further ado, here’s how KDE Linux evolved in July:
This month, Thomas Duckworth and Bhushan Shah integrated the next-gen QA system they’ve been building!
It’s now testing tons of conditions to make sure KDE Linux continues to work as expected, and it also acts as a full-stack integration test suite. To illustrate the utility of such a thing, it’s already identified and protected users from two significant issues:
gcc from Arch Linux (already fixed).These tricky problems could only have been caught by the kind of full-stack integration test suite that KDE Linux has now.
If you’re interested in the details, Thomas Duckworth’s blog post on how the system works is worth a read. Thanks very much to Thomas and Bhushan for building this lovely system!
Hadi Chokr implemented some kernel-hardening tweaks we learned about from the SecureBlue project that were relevant to KDE Linux and wouldn’t noticeably burden users.
Nate Graham removed the kernel modules for various hardware watchdogs that aren’t relevant for desktop use, which slightly reduces CPU usage and improves boot times.
Thomas Duckworth switched the CUPS printing system to use socket activation, which allows its services to only run when needed.
Hadi Chokr implemented a major improvement to the “Package Compatibility Helper” tool that now allows it to — with the user’s consent — download software from Flathub to handle files that the user tries to open, but that nothing on the system can currently open.
Hadi then made this work for Java apps; the first time you try to launch one, the tool will ask you if you want to download a Java Runtime Environment (JRE). If you approve, it will do so and then launch the app using the JRE:
After that, Hadi implemented support for DOS apps; trying to launch one will offer up DOSBox. Now you can have that authentic 1993 Doom experience:
This system can be extended to support even more things in the future! And it’s been written in a generic enough way that it would be useful for any other image-based OS using Flatpak, as well.
Philip Grant fixed the mechanism that ensures that existing KDE Linux systems have the same Flatpaks installed as are pre-loaded on new systems, as it had various bugs that prevented it from working properly.
David Fundament fixed the script that disables USB auto-suspend for input devices so that it works with devices lacking a product name.
WenChao Zhang restored the esp4 and esp6 kernel modules that had been removed to mitigate the “DirtyFrag” vulnerability. The vulnerability has been fixed now, and missing those modules had broken IPsec VPNs, so they’re back now.
Hadi Chokr made WWAN modems work out of the box.
Thomas Duckworth documented how to use and extend the new QA system.
Nate Graham documented how to make the Fcitx 5 input method (for CJKV input) work with apps still using the XWayland compatibility layer.
Hadi Chokr documented how to set up bootloader menus so you can choose between booting KDE Linux or another OS on the same computer. However, setting up such a system is left as a manual exercise for the reader, as currently the KDE Linux installer does not yet formally support complex disk setups. This will come later.
Prajna Sariputra pre-installed vulkan-virtio, improving performance in VMs whose graphics drivers support Vulkan.
Thomas Duckworth made the set-up-systemd-extension and toggle-developer-mode tools only prompt for authentication once.
Nate Graham removed the “Push Services” library and System Settings page, because it’s not mature enough for shipping yet.
KDE Linux is making steady progress towards its Beta milestone, and is now 83% of the way there.
There’s lots to do! If you’re a fan of the project, please help out; there are many ways:
Time for another bi-monthly update on what happened around Itinerary! Since the previous report there’s a new combined journey view, support for ride sharing services and new Apple Wallet pass formats, among many other things.
With more and more journeys being backed by online realtime and schedule data, access to the journey details (intermediate stops, journey map view, etc) via nested actions has become increasingly cumbersome. Therefore Jonah redesigned the details pages for all transport entries (trains, buses, ferries, flights) to have a new bottom toolbar to easily access that information.

The journey details view now also allows to query public transport departures at any intermediate stop, which is useful e.g. when doing manual rerouting in case of more complex disruptions.
After Transitous got support for ride sharing earlier this year, this has now also reached out client applications. Both Itinerary and KTrip have a mode filter for this now, and Itinerary can add ride sharing trips to the timeline.

Itinerary can now display a new variant of the Apple Wallet pass format, so-called “poster event tickets”. Conceptually those are similar to the existing event tickets but have very different layout and content, which wouldn’t render at all so far.

The background blur effect and some of the font sizes are still off, but at least the relevant content is now displayed correctly.
There’s also a few format additions affecting all pass types that are now supported:
A few gaps in the existing format support were also fixed while at it:
Besides the visual representation Apple Wallet passes can in newer versions also contain machine-readable semantic information about their content, something that is now used in the travel document extractor as well.
Thanks to Jonah’s work, MOTIS, the routing engine behind Transitous got support for the GTFS Transit Ticketing Extension. This makes booking links available for more operators, which are then shown by Itinerary or KTrip.
There has been generic work on platform integration for all of KDE’s (mobile) apps, which of course also benefits Itinerary.
For Android there’s a dedicated blog post. Since then locale-aware comparisons have been fixed in Qt (for 6.13), and Itinerary got built-in crash reporting that is already helping during development. Some necessary changes to finally fix not being able to open files from cloud shares is still stuck in review though.
For Linux the focus has been on permission checks and GPS access in a Flatpak sandbox (blog post). The foundation for the Qt permission API to support the Flatpak persmission system has been integrated meanwhile, for Qt 6.13.
There also have been efforts on evolving and standardizing modelling and mapping of indoor spaces in OpenStreetMap. While that is of course done with the entire OSM ecosystem in mind, it also benefits Itinerary, Transitous and Kongress. There it helps with improving routing through buildings and with visualizing building interiors.
The previous report had mentioned work on improving the support for GBFS v3 sharing vehicle data. This continued and now also has some more visibile results:

A few members of the Transitous community will be at State of the Map 2026 in Paris end of August, and I’ll be speaking about Transitous there.
In September there’s KDE Akademy 2026 in Graz, which is probably one of the largest gatherings of the Itinerary community. I’ll be presenting how continuous delivery helps Itinerary with QA.

Beginning of October we have the second Open Transport Community Conference in Bern, both the Transitous and the Itinerary community will be present there. A few tickets are still available.
This has been made possible thanks to your travel document donations!
All of this also directly benefits KTrip.
Feedback and travel document samples are very much welcome, as are all other forms of contributions. Feel free to join us in the KDE Itinerary Matrix channel.
Welcome to a new issue of This Week in Plasma!
…but before we start, here’s a quick reminder that we’ve entered the last week to submit your proposal for the next KDE Goals cycle! If you’re not ready to champion a goal, you can still get involved by joining one of the existing proposals as a contributor or supporter.
And now, without further ado…
In addition to the headliner feature and expected UI improvements and bug fixes, this week features some promising technical and performance improvements. Have a look:
You can now make the emojis in the Emoji Selector window bigger or smaller. (Jason Uithol, plasma-desktop MR #3878)
On System Settings’ Display Configuration page, you can now move screens pixel-by-pixel using the arrow keys while in layout editing mode. (Antti Savolainen, kscreen MR #476)
The Emoji Selector window is now always tall enough to accommodate its sidebar without scrolling. (Christoph Wolk, KDE Bugzilla #523090)
Spectacle now detects QR codes in screenshots that you take in such a manner that the main UI is never shown; if you click “Annotate” from the notification about it, the QR code will be detected there. (Kai Uwe Broulik, KDE Bugzilla #521097)
In Spectacle’s settings window, image quality controls are now only available for image types whose quality level is adjustable. (Zhora Zmeykin, spectacle MR #568)
Clarified the instructions on System Settings’s Remote Desktop page a little bit. (Nate Graham, krdp MR #224 and krdp MR #225)
Modernized the UI for the Kup backup system’s System Tray widget, so now it matches other Plasma widgets that can similarly show multiple items, each with their own actions. (Bharadwaj Raju and Tomáš Hnyk, kup MR #53 and kup MR #54)
Fixed a case where the ksystemstats background service could crash seemingly randomly. (Méven Car, KDE Bugzilla #523562)
Fixed a recent regression that made blank document icons appear in the notification history view. (Kai Uwe Broulik, KDE Bugzilla #522846)
Fixed a bug that could make extremely long words in Plasma tooltips overflow rather than wrapping. (Nate Graham, KDE Bugzilla #523614)
Fixed a bug that made third-party widgets fail to inhibit power management more than once. (Vincent de Robert, KDE Bugzilla #523605)
Fixed a visual glitch where the highlight area for expanded list items in various System Tray widgets would sometimes be too small to fit its contents. (Bharadwaj Raju, KDE Bugzilla #506295)
Fixed an issue that could sometimes corrupt very large screenshots taken in Spectacle when they were pasted elsewhere. (Cezar Craciunoiu, spectacle MR #566)
Opening various windows and dialogs using Kirigami components no longer makes the content scroll into view for no particularly good reason. (Manuel Alcaraz Zambrano, KDE Bugzilla #515811)
Fixed multiple issues that could make the powerdevil background process freeze or crash. (Sanford Rockowitz, ddcutil issue #581 and ddcutil issue #587)
Significantly improved performance with external GPUs. Read more about this on Xaver’s blog! (Xaver Hugl, kwin MR #7101)
You can now change the size (and effective resolution) of virtual screens created for screencasting, rather than them being fixed to a resolution of 1920 × 1080 pixels. (David Edmundson, KDE Bugzilla #512620)
Panel floating-ness can now be changed using Plasma desktop scripting. (Ramil Nurmanov, KDE Bugzilla #521549)
KWin now recognizes the “Pick up phone” and “Hang up phone” keys on some keyboards, allowing them to be used in keyboard shortcuts to trigger actions. (Méven Car, kwin MR #7892)
Fixed a performance issue that could make Plasma freeze when it sent a notification with a lot of emojis in it. (Devin Lin, KDE Bugzilla #508070)
KDE has become important in the world, and your time and contributions have helped us get there. As we grow, we need your support to keep KDE sustainable.
Would you like to help put together this weekly report? Introduce yourself in the Matrix room and join the team!
Beyond that, you can help KDE by directly getting involved in any other projects. Donating time is actually more impactful than donating money. Each contributor makes a huge difference in KDE — you are not a number or a cog in a machine! You don’t have to be a programmer, either; many other opportunities exist.
You can also help out by making a donation! This helps cover operational costs, salaries, travel expenses for contributors, and in general just keeps KDE bringing Free Software to the world.
Push a commit to the relevant merge request on invent.kde.org.
Let’s go for my web review for the week 2026-31.
Tags: tech, hardware, supply-chain, complexity
Interesting piece which shows very well the complexity of the hardware supply chain. The parts which matter the most are largely ignored by everyone.
https://negroniventurestudios.com/2026/07/28/sovereignty-is-a-substrate/
Tags: tech, ai, machine-learning, gpt, copilot
Funny, I was using that exact same term recently: “brute-force driven development”. It describes fairly well how the harnesses work.
https://mir.aculo.us/do-llms-know-how-to-make-software-no/
Tags: tech, systemd
Don’t forget, it’s all namespaces!
https://utcc.utoronto.ca/~cks/space/blog/linux/SystemdPrivateTmpWhere
Tags: tech, databases, design, pattern
Interesting pattern for managing materialized views over a long time.
Tags: tech, cpu, amd, performance
They’re definitely handling this part right, they seem well ahead everyone else.
https://lemire.me/blog/2026/07/25/memory-level-parallelism-amd-is-the-king/
Tags: tech, c++, standard, safety, reliability
More signs of C++26 being an important new standard for reliability and safety.
https://www.sandordargo.com/blog/2026/07/29/cpp26-reduces-undefined-behaviour
Tags: tech, c++, safety
This is a bigger trap than it sounds. It is very easy to fall into it.
https://kttnr.net/blog/cpp-float-to-int-conversion-undefined-behavior/
Tags: tech, web, webgpu, graphics
Curious about WebGPU? This looks like it’ll become a very good resource for that.
https://eliemichel.github.io/LearnWebGPU/
Tags: tech, web, standard
This is very comprehensive! It is also overwhelming… So many things to think about when making a website nowadays.
https://specification.website/
Tags: tech, architecture, microservices
Since I still hear about “microservices” more often than I’d like to. Here is another piece which points the trade-offs and that really there’s no one size fits all.
https://var0.xyz/posts/what-even-are-microservices.html
Tags: tech, codereview
There are indeed cases where it’s important to provide more context on the code which changed following up a comment by the reviewer.
https://testing.googleblog.com/2026/05/code-review-responses-add-context-when.html?m=1
Tags: tech, engineering, leadership, problem-solving
Good approach, you indeed need to immerse yourself in the context and see the recurring patterns. That’s the best way to figure out impactful solutions to recurring issues.
https://lalitm.com/post/find-problems-staff-engineer/
Tags: tech, storage, resources, procrastination
Interesting take, it’s more than just about hard drives being full. Indeed, there are many things on which we tend to procrastinate. But on the other hand… so many budgets to track otherwise!
https://www.marginalia.nu/log/a_139_hdd/
Tags: tech, software, engineering, agile, craftsmanship
Very interesting series I previously missed. It explores if software engineering is really engineering, and the differences with other engineering fields. Quite a few nice lessons to draw from it.
https://www.hillelwayne.com/tags/crossover-project/
Tags: tech, quality, kaizen, japan
Wondering how that works when it runs properly? Here is an example of a Kaizen board in a japanese factory.
https://www.leanblog.org/2026/07/kaizen-board-manager-comments/
Bye for now!
Performance on “secondary” GPUs has historically been suboptimal on Linux, especially with external GPUs. Let’s take a look at why it’s slow, and how we’re finally fixing it.
To know how things work with multiple GPUs, we first need to look at how applications present images in single GPU systems.
With Wayland, the linux-dmabuf protocol is used for sharing images from applications to the compositor. The compositor advertises which GPU it’s using, and a list of drm formats1 and format modifiers2 it can make use of.
The application then allocates a dma-buf (direct memory access buffer) for each image with one of the supported formats + modifiers on the GPU of the compositor, and sends the compositor file descriptors for these buffers to share them.
This works quite well, but only for single GPU systems. In linux-dmabuf version 5, the compositor can only advertise one GPU as being usable! The app could still attempt to pass the buffer of any GPU to the compositor, but that can fail, requiring fallbacks, and it can cause really big performance issues.
When you import a dma-buf to a GPU, the kernel tries to be helpful and automatically ensures for you that the GPU you’re using can access the buffer. This sounds nice, and can be useful, but it’s also the source of all our performance problems.
Let’s say you have a laptop with an integrated GPU, and a dedicated GPU. When you start a game on the dedicated GPU, what would happen is
To make step 3 work, the kernel would move3 the buffer to system memory. This can be really terrible for performance, since system memory is terribly slow in comparison to video memory, and the dedicated GPU has to go through the PCIe bus to access it, which has high latency.
To solve that problem, Vulkan and OpenGL drivers compare the GPU the application is using with the one the compositor advertises. If they’re not the same, then the driver will not share the buffers on the GPU with the compositor, but actually create a copy in system memory and share that copy with the compositor instead. So this would be
Now imagine you’re not playing the game on your laptop display, but you have an external display connected to the dedicated GPU. The HDMI port on a lot of laptops is wired to the dedicated GPU, so this is a really common scenario. What happens in that case is
So your game gets copied to system memory and back to video memory, for no real reason. The performance hit caused by that isn’t great in general, but it gets so much worse with external GPUs.
When all you have is one USB C cable to transfer data from and to the GPU, with high resolution monitors the bandwidth of that cable can be too small even for copying in one direction! Going in both directions completely kills performance. For example, I have a setup with
If I start vkcube (a super simple test app) on the external GPU, move it to the monitor and make it fullscreen, it only reaches 55fps!
In principle, we “just” need to stop the driver from copying the buffer around, and instead have it pass the original buffer from the dedicated GPU to the compositor. That’s exactly what I proposed version 6 of the linux-dmabuf protocol for: The compositor can support a list of GPUs instead of just one, and the application can tell the compositor which GPU it should import a given buffer into.
This all sounds nice and simple in theory, but as always, it wasn’t quite that simple in practice. There are basically three problems that needed to be solved for this change to be useful:
Thankfully, I didn’t need to do this alone. Victoria Brekenfeld from System76 implemented support for the protocol in Mesa and Smithay, the library used by the cosmic compositor.
Unfortunately, it took a long time to support the protocol in a useful way in KWin. I needed to make it
Some of this was just moving code from out drm backend to more generic places, but a lot of it required doing things from scratch. Especially GPU reset handling was challenging because KWin’s effects APIs make a lot of assumptions about OpenGL contexts and didn’t support just stopping rendering a frame once it started.
While working on this, I also added Vulkan support to KWin specifically to make the multi GPU copies as fast as possible, which also took some time. As a positive side-effect though, we now have basic Vulkan infrastructure in KWin that can be used for a future Vulkan renderer.
Finally, just over 2 years after I first proposed the protocol, we had complete enough implementations to prove it works as expected and the protocol was merged. Since then, the KWin implementation was merged, the Mesa implementation should be merged soon and Nvidia has an (as of time of writing, unreleased) implementation of the protocol in their driver as well.
So, how much does this actually help? With vkcube, we go from 55 fps to the full 120 fps of the monitor, but that’s hardly a practically relevant test.
So I fired up Cyberpunk 2077 with the “low” graphics preset and it went from 27 fps with Mesa main to 50 fps with linux-dmabuf v6. That’s more than 80% better performance!
| Mesa main | Mesa with dmabuf v6 |
|---|---|
![]() | ![]() |
From playing around a bit with the graphics settings, it seems likely that the game is bottlenecked by the USB C bandwidth, so the performance uplift could be even better with additional driver optimizations.
I haven’t been able to benchmark the impact of dmabuf v6 on “normal” laptop setups, because I don’t yet have access to a Nvidia Vulkan driver version implementing the protocol, and I don’t have a laptop with a dedicated AMD GPU. If I had to guess though, I’d expect improvements there to be much more moderate, probably something in the 5-10% range. I’ll update this post once I know more.
However, this performance uplift comes with two big caveats…
With the current KWin implementation, compositing always happens on the “primary” GPU. On laptops, by default that’s whatever GPU the internal display was connected to when KWin started. This means you can only get those large benefits if the game gets direct scanout.
My rx 5700 XT doesn’t have support for color pipelines, so I only get the performance benefit if HDR is disabled, night light is disabled and no color profile is used. I already have a merge request to lift that restriction though, stay tuned for part 2 to find out more about that!
There is another caveat though, and that’s a far bigger challenge: Most games still run on X11, and implementing the protocol (in a useful way) in Xwayland is incredibly challenging because of some assumptions X11 makes. I don’t know how that could be fixed, or even if it’s feasible at all, so for now, you can only get these benefits with games using Wayland directly.
For a lot of native games, using SDL_VIDEODRIVER=wayland does the trick, and for most Windows games, you can use Proton forks with the Wine Wayland driver. In my experience, Wine Wayland works really well and even HDR just works™ with it nowadays.
I attended the GSoC Alumni Camp in Delhi, it was an amazing opportunity to make people who are already familiar with open source aware of KDE Community and I was actually able to do that. The event itself was from 8:00 A.M. to 10:30 P.M. at night. The event started off with a formal opening session. Soon after was the scavenger hunt (we were hunting people!) it was a 5x5 grid where you needed to get signatures of people who fit the question in the box. A few of them were :
I also hosted one of the first unconference sessions titled:
From GSoC Student to Maintainer/Mentor
I wasn't expecting a large audience, but at one point the room was at its capacity around 40 attendees.
The audience included:
The discussion focused on contributor retention after GSoC and how organizations can better support contributors beyond the program. It led to some interesting discussions where we found out what some organisations are doing.
GSoC contributors naturally become subject matter experts for the components they build. When new issues, bug reports, or pull requests relate to their work, proactively invite them to participate in the discussion or review. This helps contributors feel that their expertise is valued and keeps them engaged with the project beyond GSoC.
Complex pull requests often require focused reviews and may take longer than isolated bug fixes. While taking the necessary time for a thorough review is important, mentors should acknowledge review requests and, where possible, communicate an expected timeline. Even a brief acknowledgment improves the contributor experience.
Explore using the GSoC organization stipend to support promising contributors after the program ends. This could fund continued maintenance or feature development through a transparent platform such as Open Collective, allowing contributors to invoice for their work and remain actively involved with the project.
Mentoring requires a significant investment of time in reviewing code, guiding contributors, and providing technical support. Consider allocating a portion of the organization stipend to compensate mentors, recognizing their efforts and encouraging long-term participation.
Another topic that generated considerable interest was KDE's support for its contributors.
I talked about how KDE sponsors some students to attend Akademy, and how I was also sponsored to attend the event, which a lot of people agreed organizations should've done (some did, a lot didn't) but a lot of people agreed that when an organization consider these things contributors stay.
After all the unconferences ended a lot of people came up to me saying mine was the best and I managed and engaged everyone in the best way possible ( I was on cloud 9).
One of the highlights was being selected to give a lightning talk. Only 18 participants were chosen, and I was one of them.
My GSoC project Join KDE is an advertisement for KDE itself, so the project itself became an easy conversation starter. It was a great opportunity to introduce KDE and make more people aware of the organization.
Although I did fumble the last part of my presentation it was more of me being confused where my slide went (some slides were misplaced) aside from that it went as any other informative talk but hey I was funny on the stage (refer to the pics) so people remember me! You win some you lose some, oh well.
Outside the sessions, I had some interesting discussions with contributors from different organizations. Some contributors showed interest in working wwith us while some showed interest in our eduction/science side but honestly it's hard to bring contributors over as they're in different domains, org admins/mentors or they're busy with their careers.
I had a conversation with a maintainer from the SU2 Foundation, whose work focuses on computational fluid dynamics.
We discussed KDE's scientific and educational initiatives, including KDE for Scientists and several education-related projects. I also shared the KDE For You website as an introduction to the wider KDE ecosystem.
The conversations continued during the after-party on the following day.
I met a group of students who had become interested in open source after interacting with contributors throughout the event. They had originally attended as friends of another contributor.
One of them is now actively looking for a project to begin contributing to within KDE. YAYYY!
Several first-time contributors approached me asking about projects suitable for beginners.
I introduced them to a number of KDE projects and explained possible contribution paths.
But the same issue they're busy with the beginning of their careers.
The Alumni Camp was one of the best ways to make people aware of KDE and I tried my best while i had fun ( we played uno there! Will bill the cards to the organization jkjk), a lot of people seemed intrigued and asked me to share some stuff about KDE to them or they'll try it on their own. Met someone from GNOME (they didn't get any lightning talk HA! I know, I know no inter project fighting that's bad) had some good conversations, teased the person from GNOME, had breakfast with them, and tried to make the most of the unconference session and the lightning talks to at least get people to know the name KDE!







Today we're releasing Krita 5.3.3 and 6.0.3, containing many bugfixes and improvements across the board.
On Android, version 5.3.3 lets you support Krita's development directly through the application. This goes through the Play Store, so if you have a device without Google services or are using a debug or nightly version of Krita, it won't be available and instead will show you donation links.
In return for supporting Krita, you'll be able to download resource bundles directly in the application, including the paid Digital Atelier bundle. The splash screen and welcome page will also tell you about the supporter packs or donation links. You are not required to make any purchases, no features are locked behind a paywall and you won't get nagged about it while you're actually working. You can also of course still manually import resource bundles, the downloads are just a convenience feature.
For a longer explanation and a way to give feedback or ideas, take a look at this forum post.
Special thanks to Freya Lupen and Elena Sagalaeva, for multiple bug fixes, as well as the many newcomers who contributed to this release (named in the changelog).
⚠️ Warning
We consider Krita 5.3.3 suitable for productive work; 6.0.3 is, because of the many changes from Qt5 to Qt6 more experimental.
If you're using the portable zip files, just open the zip file in Explorer and drag the folder somewhere convenient, then double-click on the Krita icon in the folder. This will not impact an installed version of Krita, though it will share your settings and custom resources with your regular installed version of Krita. For reporting crashes, also get the debug symbols folder.
ⓘ Note
We are no longer making 32-bit Windows builds.
64 bits Windows Installer: krita-x64-5.3.3-setup.exe
Portable 64 bits Windows: krita-x64-5.3.3.zip
Note: starting with recent releases, the minimum supported distro versions may change.
⚠️ Warning
Starting with recent AppImage runtime updates, some AppImageLauncher versions may be incompatible. See AppImage runtime docs for troubleshooting.
⚠️ Warning
With Krita 5.3.3 release minimum supported MacOS version has increased from 10.14 (Mojave) to 10.15 (Catalina)
Krita on Android is still beta; tablets only.
Source code is the same as 6.0.3. See the 6.0.3 section.
For all downloads, visit https://download.kde.org/stable/krita/5.3.3/ and click on "Details" to get the hashes.
The Linux AppImage and the source tarballs are signed. You can retrieve the public key here. The signatures are here (filenames ending in .sig).
If you're using the portable zip files, just open the zip file in Explorer and drag the folder somewhere convenient, then double-click on the Krita icon in the folder. This will not impact an installed version of Krita, though it will share your settings and custom resources with your regular installed version of Krita. For reporting crashes, also get the debug symbols folder.
ⓘ Note
We are no longer making 32-bit Windows builds.
64 bits Windows Installer: krita-x64-6.0.3-setup.exe
Portable 64 bits Windows: krita-x64-6.0.3.zip
Note: starting with recent releases, the minimum supported distro versions may change.
⚠️ Warning
Starting with recent AppImage runtime updates, some AppImageLauncher versions may be incompatible. See AppImage runtime docs for troubleshooting.
Note: minimum supported MacOS may change between releases.
Krita 6.0.3 is not yet functional on Android, so we are not making APK's available for sideloading.
For all downloads, visit https://download.kde.org/stable/krita/6.0.3/ and click on "Details" to get the hashes.
The Linux AppImage and the source tarballs are signed. You can retrieve the public key here. The signatures are here (filenames ending in .sig).
There is a bug in KDE's bug tracker that is almost as old as some of our
contributors: bug 342056,
"Ridiculously slow file copy (multiple small files)", reported by Alexander
Nestorov back in 2014. The report is blunt: copying a 15 GB folder of roughly 3
million small files took 5 to 10 hours in KDE, versus about 20 minutes with
rsync. One commenter summed up the mood:
I generally use cp and rsync instead of dolphin for anything more than a few files.
That bug has been stuck in my head for a while, so this post is about finally
fixing it. I have been working on KIO's copy path, and I want to walk
through where the time was going, some history that explains why, and show
numbers across KIO versions including a plain cp for reference.
At with any optimization, let's measure first:
Where a KIO 6.28 copy of 5000 small files spends its blocking time, and there
is no single hotspot. Each file blocks in a burst of short syscalls: reading the
mount table (/proc/self/mountinfo), opening the source and destination, and
round-tripping a command to the worker over an internal socket. The socket
round-trips, the send and receive plus the waits for each reply, are the frames
highlighted in red, about 15% of the blocking here, spread as thin slivers
across both threads because every one of the thousands of files pays them. The
frames in green are the real filesystem work the copy cannot avoid: the statx
and openat calls, copy_file_range moving the bytes, and the ext4 metadata
updates beneath them. That per-file storm, not any single call, is what the rest
of this post discusses.
(Off-CPU flame graph from sched:sched_switch, weighted by number of blocking
switches; click to open the full SVG.)
KIO is the layer behind almost every file operation in KDE software, from Dolphin's copy
and paste to the network transparency that lets you open sftp:// or smb://
URLs as if they were local. Its design goes back to the KDE 2 days, around the
year 2000. Back then the answer to "how do I do I/O without freezing the UI" was
not a thread but a separate process: a worker (we used to call them kioslaves)
is launched for a protocol and talks to the application over a socket. This
predates usable threading on Linux (Native POSIX Thread
Library only landed
in Linux 2.6 in 2003), so processes plus socket IPC was the portable, robust
choice, and it still is for network protocols today: if an smb:// worker
crashes, your file manager does not go down with it.
The flip side is cost. Every request and its reply are serialized and sent over
that socket, with an event-loop hop on each side. For file:// that overhead
buys you nothing, because there is no untrusted network on the other end, just
the local disk.
In 2022 David Faure changed that: Implement running KIO workers in-process
using a thread landed in Frameworks 5.95. Since then the file worker runs on a thread inside
the application instead of as a separate process (other protocols stay
out-of-process for robustness). That removed process launch and context-switch
cost.
There was still a catch that had been hiding in plain sight: even in-process, the worker thread and the application talked to each other over a socketpair, serializing every command as if they were separate processes. Once the thread was used, that socket was pure overhead.
That's the red highlight in the first flamegraph.
So in-process workers now use a real in-memory transport instead of a loopback
socket. A new ThreadConnectionBackend handles commands, and for reads the actual
data buffer, straight to the peer thread, with no serialization and no syscall,
which makes in-process file reads zero-copy. This is the biggest single jump in
the numbers below, and it has landed on master for 6.29
(kio!2279).
The changes above make each command cheap. The remaining cost is that there are
still so many of them: copying N files is N separate file_copy jobs, each one
going through the job scheduler and taking its own round-trip to the worker. For
many small files that fixed per-file cost, not the data, is what dominates.
CopyJob can dispatch a whole batch of plain local-to-local files to the worker
in one command, and the worker copies them (using copy_file_range,
and reflink on filesystems like Btrfs or XFS that support it). Each file still
gets its progress signal, its byte accounting, its undo entry, and anything
the worker cannot do blindly — an existing destination, an unreadable source, a
rename or skip decision — is handed back to the normal per-file path. The gate is
conservative on purpose so a hung mount can never freeze the batch
(kio!2282).
The same copy on 6.29 with batch-copy: the red socket round-trips are gone. Two
things removed them: the in-memory transport from the previous section (no
socketpair at all) and batch-copy folding a whole run of files into one command
instead of one round-trip each. What is left is real filesystem work: the green
frames are the copy itself, copy_file_range moving the bytes, the openat and
statx calls, and the ext4 metadata beneath them. The wide plateau that is not
green is the benchmark loop deleting each pass's files before the next run
(unlink), which is teardown rather than part of the copy.
Before copying, CopyJob stats every source, which is another per-file
round-trip. The follow-up batches the stat phase over the same in-process lane.
This is the batch-copy-stat column below.
Both of these are under review and targeted at a release after 6.29, so treat their columns in the table as a preview of what is coming rather than something you can install today.
Methodology: a 13th-gen Intel Core i7-1365U laptop, everything built
RelWithDebInfo without any sanitizer, copying onto a real ext4 volume (so no
reflink shortcut, copy_file_range moves real bytes). Each KIO version supplies
both its own libKIOCore and its own kio_file worker. Times are the median of
5 runs (3 for the large set) after a discarded warm-up, so caches are warm and
equal for every version. cp -r --preserve=mode,timestamps is included as the
floor, since that is what the bug reporter reached for instead of Dolphin.
5000 files of 4 KB each (the many-small-files case from the bug):
| Version | Median time |
|---|---|
cp -r (coreutils) | 81 ms |
| KIO 6.28.0 | 1616 ms |
| KIO 6.29-dev (master) | 396 ms |
| KIO 6.29-dev + batch-copy | 88 ms |
| KIO 6.29-dev + batch-copy-stat | 93 ms |
1000 files of 5 MB each (bulk data, where the copy is I/O-bound):
| Version | Median time |
|---|---|
cp -r (coreutils) | 1312 ms |
| KIO 6.28.0 | 1997 ms |
| KIO 6.29-dev (master) | 1687 ms |
| KIO 6.29-dev + batch-copy | 1506 ms |
| KIO 6.29-dev + batch-copy-stat | 1454 ms |
The small-files case is the story. KIO 6.28 was about 20x slower than cp,
which is exactly the ratio the 2014 report complained about. Removing the socket
for in-process workers, together with no longer probing the destination
filesystem once per file, takes it from about 1.6 s to 0.4 s (roughly 4x).
Batching the copy takes it to 88 ms, essentially cp speed and about 18x faster
than 6.28. That "I use cp instead of dolphin" line finally has an answer.
The large-file case was already well covered before any of this work, and the
table shows it: the copy is bound by moving the bytes, so even KIO 6.28 stayed
close to cp there, and the per-file optimizations barely move the number
(batch-copy lands within about 15% of cp). That is the whole reason this
effort targets many small files instead, where the fixed per-file cost, not the
data, is what dominates.
batch-copy and batch-copy-stat come out tied here: the benchmark copies a single
directory, so its entries arrive in one listing and batch-stat has nothing to
batch. It helps the other case, copying a large selection of individual files
that would otherwise be one stat round-trip each. Since it removes the
round-trip and not the stat call, the win is largest when stats are cheap, not
when the disk is slow. Read the two as equal on this test.
And cp will almost certainly stay a little ahead, by design: KIO does more
than copy the bytes. It reports per-file progress, can be paused and cancelled,
keeps an undo record, preserves permissions and timestamps, resolves conflicts,
and tells any open file manager what changed so its view refreshes. That work is
not free, and the goal was never to beat cp, only to make the local case fast
enough that reaching for cp instead of Dolphin stops being the obvious choice.
These are laptop numbers on one ext4 disk with warm caches, meant to compare versions, not to be absolute. On Btrfs or XFS the batch path reflinks instead of copying, which changes the large-file picture entirely. The batch fast path only engages for plain local-to-local copies on a responsive filesystem; anything else (network, FAT/NTFS, conflicts needing a dialog) falls back to the existing per-file path, unchanged.
Thanks to David Faure for the in-process worker threads that made all of this possible, to Frank Reininghaus for the earlier listing fixes, and to Alexander Nestorov for a bug report that aged well enough to still be worth closing.
That's all, folks.
Months ago, some distributions accidentally removed cryfs and encfs from Vaults dependencies (temporarily). And some distributions are removing them intentionally from their package repositories (at least, for the time being).
It might be a good idea to switch your vaults to gocrtyptfs.
There is no automatic process for this, just create a new vault (it will be gocryptfs-based – other backends have been removed from the UI in the latest versions) and copy the data from the old one there.
To avoid users thinking there is something serious going on, this is some background on changes:
So, nothing important has happened. Your vaults are as safe as they always were.
It is just that it might bring you a headache if the backend you use for your vaults disappeared after you update your system.
And headaches for me when I get bug reports that Vaults no longer support encfs or cryfs :)
