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AMDGPU & Radeon DDX Updated - Better 2D Performance, Tear Free, DRI3 Default

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  • AMDGPU & Radeon DDX Updated - Better 2D Performance, Tear Free, DRI3 Default

    Phoronix: AMDGPU & Radeon DDX Updated - Better 2D Performance, Tear Free, DRI3 Default

    Necessitated by the new X.Org Server 1.19 release are new official releases to xf86-video-amdgpu and xf86-video-ati. But besides adding support for the xorg-server 1.19, there are also new features with these being infrequent updates to the DDX driver...

    http://www.phoronix.com/scan.php?pag...U-1.19-Updates

  • #2
    Sounds great! Are the performance improvements mainly because of glamor optimizations as discussed recently or are they specific to ddx driver?

    Comment


    • #3
      the tear free improvements. would these just be there when you upgrade to these versions, or would this be something you need to turn on. if you need to turn it on, how would one go about doing that.

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      • #4
        Would be nice to have xfce tear free by default.

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        • #5
          I recall similar tear-free options that have a negative performance impact. Is that the case here? The man page doesn't mention it. Is there a particular reason why it's not enabled by default?

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          • #6
            Originally posted by Chewi View Post
            I recall similar tear-free options that have a negative performance impact. Is that the case here? The man page doesn't mention it. Is there a particular reason why it's not enabled by default?
            Depends on what you mean. Tearing is a problem caused by the video card updating its frame buffer during a monitor refresh. The only way to fix tearing is to slow down the card, keeping it in sync with the monitor. Technically, this is a "negative performance impact", but it only affects frames you weren't seeing anyway or were seeing only partially.

            On another note, kudos to AMD for speedy X support, this was one of the major issues keeping me in the green camp.

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            • #7
              Originally posted by gerry_here_to_learn View Post
              the tear free improvements. would these just be there when you upgrade to these versions, or would this be something you need to turn on. if you need to turn it on, how would one go about doing that.
              There seems to be no GUI for this (on my machine at least). The user needs to edit /etc/X11/xorg.conf:

              Code:
              ...
              Section "Device"
                      Identifier  "Device[0]-0"
                      Driver      "amdgpu"
                      #Driver      "radeon"
                      #Driver      "modesetting"
                      Option      "TearFree" "1"
                      #BusID       "PCI:0:1:0"        # Integrated GPU
                      #BusID       "PCI:1:0:0"        # Discrete GPU
              EndSection
              ...

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              • #8
                Originally posted by bug77 View Post
                Depends on what you mean. Tearing is a problem caused by the video card updating its frame buffer during a monitor refresh. The only way to fix tearing is to slow down the card, keeping it in sync with the monitor. Technically, this is a "negative performance impact", but it only affects frames you weren't seeing anyway or were seeing only partially.
                For example, EXAVSync says:

                This option attempts to avoid tearing by stalling the engine until the display controller has passed the destination region. It reduces tearing at the cost of performance and has been known to cause instability on some chips. The default is off.
                While TearFree says:

                Enable tearing prevention using the hardware page flipping mechanism. This option currently doesn't have any effect for rotated CRTCs. It requires allocating two separate scanout buffers for each non-rotated CRTC. Enabling this option currently disables Option EnablePageFlip. The default is off.
                It doesn't say whether allocating two separate scanout buffers is especially bad.

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                • #9
                  Originally posted by Chewi View Post

                  For example, EXAVSync says:



                  While TearFree says:



                  It doesn't say whether allocating two separate scanout buffers is especially bad.
                  Technical implementation doesn't matter. Tearing is caused by your video card rendering more frames than your monitor can show.
                  Tearing is when you monitor can display 60 frames each second and your card can render 90. If I fix tearing and make the card render only 60 fps, are you actually loosing performance?

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                  • #10
                    If that's the only kind of performance you're really losing, that's fine! The EXAVSync description just made it sound worse.

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