KDE On Wayland: "The Biggest Thing Needed Now Is Adoption By 3rd Party Apps"

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  • mSparks
    Senior Member
    • Oct 2007
    • 2078

    Originally posted by oiaohm View Post

    There is a problem here.
    A considerable amount of people assume Wayland isn’t particularly suitable for gaming, usually because you can’t turn off the compositor. This post will challenge that assumption and see how the current state of gaming on Wayland is, with a focus on KWin, KDEs compositor.

    We do not have these tests after tearing allowed came option/official feature under KDE.

    So there is no current evidence to support you claim that Xorg with no compositors is faster than KDE wayland these days. This old evidence does highly suggest the input latency today could be exactly the same and all the difference was that KDE was by default forbidding tearing. Reality someone need to rerun those 2021 tests with the new compositors and see where we in fact land.
    "turning off tearing" (disabling vsync in X11 lingo) is a completely different thing than disabling compositing (fancy window animation effects and drawing over each other) which cannot be disabled in wayland - there is no concept of a separate display server in wayland, its compositor or black screen.

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    • ms178
      Senior Member
      • Sep 2018
      • 1709

      Originally posted by smitty3268 View Post

      From what I've seen, I highly doubt that Roman or the Kwin devs would ever choose to work with one another again. Too much bad blood.

      That doesn't mean they won't work with wlroots, though.
      Well, personal animosities aside, they would share the same technical goal and wlroots underneath once again. That would leave room for cooperation, sharing precious developer time.

      Comment

      • oiaohm
        Senior Member
        • Mar 2017
        • 8432

        Originally posted by mSparks View Post
        "turning off tearing" (disabling vsync in X11 lingo) is a completely different thing than disabling compositing (fancy window animation effects and drawing over each other) which cannot be disabled in wayland - there is no concept of a separate display server in wayland, its compositor or black screen.
        Phoronix, Linux Hardware Reviews, Linux hardware benchmarks, Linux server benchmarks, Linux benchmarking, Desktop Linux, Linux performance, Open Source graphics, Linux How To, Ubuntu benchmarks, Ubuntu hardware, Phoronix Test Suite


        Again wrong. What you you think Direct Scan-Out features do. The performance losses in 2021 test align with tearing being forbid not windows animations.

        Direct scan-out tell GPU take this DMABUF from X application that is full screen and output it to screen as fast as configured.

        Separate display server is kind of a joke. X11 bare metal only performs as well as it does because opengl/vulkan uses a direct scanout mode and bipass the complete thing.

        No X11 server no output either right mSparks. Also remember drm leasing used by VR. Yes the fastest output is not wayland or x11 is take out a drm lease on the output so bypassing X11 server and the Wayland compositor completely.

        Yes X11 display server or Wayland compositor are both overhead. It would be really useful of someone redid those 2021 benchmarks but this time with drm lease under X11 and Wayland and direct to linux drm in the mix. Yes direct to linux drm would be lowest overhead possible while using the Linux kernel.

        There is high possibility that X11 bare metal with no compositor performance is no difference to Wayland compositors in Direct Scan Out mode. Like it or not x11 bare metal without a compositor running display server still has overhead.

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        • mSparks
          Senior Member
          • Oct 2007
          • 2078

          Originally posted by oiaohm View Post
          Again wrong. What you you think Direct Scan-Out features do.
          not "turn off tearing".
          Originally posted by oiaohm View Post
          DMABUF
          DMABUF is a 100% CPU function and has no place in high performance graphics.
          Originally posted by oiaohm View Post
          Also remember drm leasing used by VR.
          Not by the CPU.
          Originally posted by oiaohm View Post
          No X11 server no output either right mSparks.
          Indeed, if you have no protocol to transfer keyboard/video/mouse between applications those applications cannot process the keyboard/video/mouse.
          At least you got something right.
          Originally posted by oiaohm View Post
          so bypassing X11 server and the Wayland compositor completely.
          LOL, no, keyboard, mouse and other inputs such as head tracking are NOT passed directly to video memory, you were doing so well, then a sentance after decide that even with no protocol to transfer keyboard/video/mouse between applications those applications can process the keyboard/video/mouse.
          Originally posted by oiaohm View Post
          Yes X11 display server or Wayland compositor are both overhead.
          INPUT latancy, X11 has none, Wayland has a lot. Because Wayland has a ton of logic added so that screen recording, multiple screens and the mouse cursor work like dogshit so the screen never tears, and turning tearing off does not remove that logic, neither does Direct Scan-Out.

          Comment

          • oiaohm
            Senior Member
            • Mar 2017
            • 8432

            Originally posted by mSparks View Post
            DMABUF is a 100% CPU function and has no place in high performance graphics..
            You are aware when you are using opengl and vulkan under X11 baremetal with AMD/Intel you are using DMABUF as well. So by this statement X11 has no place in high performance graphics either when using AMD and Intel.


            Indeed, if you have no protocol to transfer keyboard/video/mouse between applications those applications cannot process the keyboard/video/mouse.
            How does VR applications do it that use DMA leasing. Directly using libinput that takes you direct to Linux kernel provide input events by edev.


            that what this does.

            Also then you have the new input capture portal. You don't need X11 or Wayland protocols to access keyboard/video/mouse under Linux. VR applications are very high performance things both X11 and Wayland have too much latency for VR headsets.

            The highest performance lowest latency graphical applications under Linux don't use X11 or Wayland and they are VR applications.

            Originally posted by mSparks View Post
            INPUT latancy, X11 has none, Wayland has a lot. Because Wayland has a ton of logic added so that screen recording, multiple screens and the mouse cursor work like dogshit so the screen never tears, and turning tearing off does not remove that logic, neither does Direct Scan-Out.
            No X11 is not zero input latency the legacy X11 input stack in fact introduces a lot of latency this is why VR applications bipass the complete area.

            There is a reason why I said I wanted to see application using DMA lease and direct DRM in the mix these would be Linux native VR applications that are in fact designed for the lowest latency..

            This is semi-redundant with #227, but its narrower scope might make it more achievable than a fully general USB device portal. For brevity I'm going to use "joystick" the same way the kernel and ud...

            Yes lots of games also go direct to evdev directly so bipass X11 input stack and if they are doing a evdev bipass they also bipass the Wayland compositor input stack using the same methods.
            Last edited by oiaohm; 19 September 2023, 11:53 AM.

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            • mSparks
              Senior Member
              • Oct 2007
              • 2078

              Originally posted by oiaohm View Post

              You are aware when you are using opengl and vulkan under X11 baremetal with AMD/Intel you are using DMABUF as well. So by this statement X11 has no place in high performance graphics either when using AMD and Intel.
              Top of the line modern AMD/Intel cards are generally vastly out performed by bottom of the line nvidia cards from nearly 10 years ago for exactly that reason.

              Comment

              • mSparks
                Senior Member
                • Oct 2007
                • 2078

                Originally posted by oiaohm View Post
                How does VR applications do it that use DMA leasing. Directly using libinput that takes you direct to Linux kernel provide input events by edev.
                Did you mean DRM leasing perhaps? never heard of DMA leasing.

                That has nothing to do with input latency and everything to do with the Wayland protocol being unable to acomplish simple tasks like render directly to a screen - BY DESIGN.

                Comment

                • oiaohm
                  Senior Member
                  • Mar 2017
                  • 8432

                  Originally posted by mSparks View Post
                  Top of the line modern AMD/Intel cards are generally vastly out performed by bottom of the line nvidia cards from nearly 10 years ago for exactly that reason.
                  Thanks for that answer. Sorry your toast.
                  Now that the sources are no longer restricted from using GPL symbols, can we please have true Linux DMABUF import support? Currently NVIDIA reports EGL_EXT_image_dma_buf_import however this is not ...

                  Our X driver uses it for reverse-PRIME support
                  I walked you straight into it. Nvidia uses DMABUF in high performance PRIME usage cases completely. Yes the Nvidia driver developers admit the issues with DMABUF and their driver is just they have not wired up all the interfaces to userspace fully.

                  Nvidia was not the answer mSparks you just proved past question you don't know this topic.
                  Last edited by oiaohm; 19 September 2023, 12:06 PM.

                  Comment

                  • oiaohm
                    Senior Member
                    • Mar 2017
                    • 8432

                    Originally posted by mSparks View Post
                    Did you mean DRM leasing perhaps? never heard of DMA leasing.
                    Dyslexia won that one I was aiming for DRM leasing and I was seeing as I was reading it back DRM leasing.

                    Comment

                    • MrCooper
                      Senior Member
                      • Aug 2008
                      • 635

                      Originally posted by mSparks View Post
                      Color calibration support
                      Wayland compositors have always been able to perform per-monitor calibration; per-window calibration is being worked on and will leap-frog Xorg (e.g. every window will always be displayed correctly).

                      multiple screen support
                      Works better with Wayland than Xorg in many ways. E.g. different refresh rates and scaling per monitor can be handled perfectly.

                      VR support
                      Should work if the Wayland compositor supports the DRM leasing protocol.

                      screen recording and streaming support
                      Works better via Pipewire than it ever did for me with Xorg.

                      high fps support
                      Works fine. Without tearing, frame rate cannot exceed the refresh rate. With tearing, apps will run at the same frame rate as with Xorg.

                      not requiring a reboot because it crashes every 5 minutes support
                      mutter crashes very rarely for me, even development snapshots.

                      mouse cursor support (it doesnt tear, but it does take 3 seconds to move)
                      Current mutter & kwin have very similar latency for mouse cursor movement as Xorg, you'll be hard-pressed to notice a difference.

                      Originally posted by mSparks View Post

                      "turning off tearing" (disabling vsync in X11 lingo) is a completely different thing than disabling compositing [...]
                      You can't have lower latency than a good Wayland compositor without tearing.​

                      Originally posted by mSparks View Post
                      INPUT latancy, X11 has none, Wayland has a lot.
                      There's no such thing as no latency. (Fundamentally because the speed of light isn't infinite)

                      Without tearing, a good Wayland compositor's latency is same as or better than Xorg.

                      With tearing, it should be a wash.

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