Hi all

On Tue, Sep 8, 2020 at 08:56, Erich Eickmeyer <eeickmeyer@fedoraproject.org> wrote:
Hi Ben, On 9/8/2020 8:28 AM, Ben Cotton wrote:
https://fedoraproject.org/wiki/Changes/WaylandByDefaultForPlasma == Summary == Change the default session selection in SDDM to prefer the Wayland-based KDE Plasma Desktop session over the X11-based one. == Owner == * Name: [[User:Ngompa|Neal Gompa]], [[User:Rdieter|Rex Dieter]], [[User:Jgrulich|Jan Grulich]] * Email: ngompa13@gmail.com, rdieter@gmail.com, jgrulich@redhat.com * Product: KDE Spin * Responsible WG: KDE SIG == Detailed Description == With KDE Plasma 5.20, the KDE Plasma desktop environment has reached a point where nearly all commonly used features in the desktop and all major applications function in the Plasma Wayland environment on all major GPUs (including NVIDIA with the proprietary driver). Starting with Plasma 5.20 in Fedora 34, we will change the default configuration for Wayland and X11 Plasma sessions so that Wayland is preferred and used by default, while permitting the X11 session to be selected as the alternative desktop environment option. == Feedback == ==== Is Wayland ready? ==== Wayland has been used by default for Fedora Workstation (which uses GNOME) since Fedora 25. And while it was somewhat immature initially, today it is a very rock-solid experience on virtually everything Fedora Workstation runs on. The change in Fedora 25 kickstarted the drive to get everything working on Wayland, and the Workstation team succeeded beyond their wildest dreams. Firefox has been Wayland-native by default since Fedora 31 as well. On the KDE side, serious work into supporting Wayland started shortly after GNOME switched to Wayland by default. Unlike GNOME, KDE has a much broader stack in its toolkit, and it has taken longer to get to a usable state. With the Plasma 5.20 release, the Wayland protocol for screencasting as well as middle-click paste finally are supported, completing the required feature set for switching to Wayland by default. ==== What about NVIDIA? ==== Plasma, in fact, ''does'' support NVIDIA GPUs with the proprietary driver on Wayland. It needs to be manually activated, which will be taken care of by the <code>kwin-wayland-nvidia</code> package. So the expectation is that all major GPUs will work just fine. ==== Why not keep using X11? ==== The fact of the matter is, Xorg is in [https://blogs.gnome.org/uraeus/2019/06/24/on-the-road-to-fedora-workstation-31/ "hard maintenance mode"] per [[User:Uraeus|Christian Schaller]] and development on it has basically stopped beyond the most critical of fixes. Combined with the rapid maturation of the Wayland session in KDE Plasma, this is the best time to make the switch and push things over the edge for the KDE ecosystem in the same way that Fedora Workstation did for the GNOME ecosystem. == Benefit to Fedora == Fedora has long been a leader in advancing the adoption of the Wayland protocol as part of the overall strategy to improve the Linux graphical software stack. Much of the quality of Wayland for GNOME can be attributed to the work done by the Fedora Workstation WG as part of advancing the GNOME platform. It is now the KDE SIG's turn to do the same for the KDE platform. By making this change, we are helping push the adoption forward for newer, more streamlined, and overall more actively developed graphics technology for the KDE ecosystem. == Scope == * Proposal owners: ** Modify {{package|kwin}} to switch to Wayland *** Split out <code>/usr/bin/kwin_x11</code> to the <code>kwin-x11</code> subpackage. *** Make {{package|kwin}} require <code>kwin-wayland</code> and recommend <code>kwin-x11</code> *** Add <code>kwin-wayland-nvidia</code> subpackage which contains <code>/usr/lib/environment.d/10-kwin-wayland-nvidia.conf</code> to set <code>$KWIN_DRM_USE_EGL_STREAMS</code> to <code>1</code>. This package will have have a Supplements dependency <code>(kwin-wayland and kmod-nvidia)</code>. ** Modify {{package|plasma-workspace}} to switch to Wayland *** Rename <code>/usr/share/xsessions/plasma.desktop</code> to <code>/usr/share/xsessions/plasma-xorg.desktop</code>, subpackage it out as <code>plasma-workspace-xorg</code>, and have it require <code>kwin-x11</code> *** Rename <code>/usr/share/wayland-sessions/plasmawayland.desktop</code> to <code>/usr/share/wayland-sessions/plasma.desktop</code> *** Make {{package|plasma-workspace}} require <code>plasma-workspace-wayland</code> and recommend <code>plasma-workspace-xorg</code> ** Modify <code>@kde-desktop</code> comps group for Fedora 34 to include <code>plasma-workspace-xorg</code> for the media. * Other developers: N/A (not applicable for this Change) * Release engineering: [https://pagure.io/releng/issue/9741 #9741] * Policies and guidelines: N/A (not needed for this Change) * Trademark approval: N/A (not needed for this Change) * Alignment with Objectives: N/A (not applicable for this Change) == Upgrade/compatibility impact == Systems using certain (very old) graphics hardware or graphics drivers (matrox, etc.) may have problems running the Wayland session. In these (rare) cases, users may have to configure SDDM to use X11. == How To Test == Log into a KDE Plasma desktop. Do any activity you would normally do in your daily desktop use: launching applications, configuring displays, etc. Things should work the same way under Wayland as they used to under X. == User Experience == The user experience should not change noticeably. == Dependencies == This mainly affects the {{package|plasma-workspace}} and {{package|kwin}} packages, and details for the changes for those packages are described in the Scope section. == Contingency Plan == * Contingency mechanism: Revert the file renames and switch <code>plasma-workspace-xorg</code> to be the required package instead of <code>plasma-workspace-wayland</code> * Contingency deadline: beta freeze * Blocks release? Yes * Blocks product? KDE Spin == Documentation == Some upstream documents about Wayland * https://community.kde.org/Plasma/Wayland * https://community.kde.org/KWin/Wayland There is currently no coherent up to date documentation about Plasma Wayland. == Release Notes == The KDE Plasma Desktop is using the Wayland display system now. X applications will continue to run transparently through XWayland.
Since Fedora Jam directly depends on the Fedora KDE Spin kickstart and carries most of its defaults, I wish someone would've talked to me about this before this became a full-fledged change proposal and officially posted. For the btrfs-by-default change, Neal was gracious enough to reach out to me and ask if I thought it would benefit Jam. As I agreed, he put my name on the list of change owners and now btrfs is the default. In this case, I have not been given the same amount of courtesy. I have done some (albiet limited) testing of Wayland, and from my tests, aside from some potential theming issues where the theme is not supporting Wayland (really Ubuntu Studio's default theme, but that isn't in use here), it seems to be mostly solid. Even the High DPI scaling does a better job on Wayland. I see no real issues with this, and would've otherwise agreed to this and been one of the change owners if one had simply asked me, but right now I'm feeling a bit of tepidness since this change directly affects Fedora Jam and I was not asked prior to it becoming an official change proposal. Perhaps there were reasons for that, but I don't know why that wouldn't be considered. Perhaps the thought process was that the change to the display compositor wouldn't affect audio, but the reality is that anything that even potentially affects CPU/GPU usage affects lowlatency and realtime audio performance and recording since the kernel can and sometimes does take time away from audio to do video-related processes. So with that, I'm really on the fence on this one. I guess I need more time to test. But, again, I wish somebody would've asked me first. -- Erich Eickmeyer Maintainer Fedora Jam

I have done some testing today using Wayland with a default Fedora Jam from Rawhide install, using Studio Controls to set-up my audio permissions, setting my CPU governor to performance, and using my built-in audio card as my test device on my Dell Inspiron 5576 Gaming Laptop which has an AMD A10 (7th gen), AMD RX540 discrete graphics, and 16GB of RAM with a SSD. I tested X11 vs Wayland.

In both cases, Jack was set to 48000Hz sample rate with a buffer size of 128 and 2 periods per buffer, which would be a typical setting when bridged to PulseAudio as was the case here. With Jack started, I started Carla and did some tests with various plugins while moving windows around, minimizing, maximizing, and other items that would work the compositor. I set tearing prevention to "only when cheap" but neither time did I notice any tearing. Additionally, Jack did not detect any Xruns (buffer over/under-runs) while using either X11 or Wayland.

With this, I also did not notice any real issues when running Wayland on this hardware, and believe that with the next Plasma release (5.20) we might actually see Plasma and Wayland more solid than ever.

Since Wayland did not interfere with any normal professional audio settings or performance, I will go ahead and give this my +1, especially since it, combined with Pipewire, may be the only way forward for Linux Audio as a whole.

--
Erich Eickmeyer
Maintainer
Fedora Jam