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Likely Radeon Gallium3D Regression On Linux 3.14 + Mesa 10.2

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  • #41
    Worst of all regressions was with the new Xserver, Mesa was about 20%

    Originally posted by curaga View Post
    Michael, this is not completely from HyperZ and so still worth investigating. We have reports from Luke and dungeon on this forum that confirm there's another regression besides the intended hyperz change.

    Luke specifically tested it, dungeon's case is media apps that do not use the Z buffer.
    In my tests, I found that with Mesa 10.2/Kernel 3.13/Xserver 1.15, framerates were cut in half. Plymouth crashes with the early Linux3.14 rc1 that I tried, blocking my disk decryption system so I have yet to test the new kernel. With Mesa 10.2 but reverting to Xserver 1.14, I got back most of the regression but was still down 10-20%. That was the part that apparently turned out to by from hyper-z in my tests.

    I got essentialy identical performance using Mesa 10.1 or Mesa 10.2 with hyper-z force-enabled in Critter (only one Z value, it's a 2d game) , but in Scorched3d,

    R600_HYPERZ=1 scorched3d

    locked up the whole x server with Hyper-Z and Mesa 10.2, with either version of X. I checked the exact same code with Mesa 10.1, no problems at all in Scorched3d.

    I am guessing the issue with the new X server relates either to the DRI 3 changeover or to the rewrite of the GLX system referred to in the changelogs.

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    • #42
      Originally posted by Luke View Post
      In my tests, I found that with Mesa 10.2/Kernel 3.13/Xserver 1.15, framerates were cut in half. Plymouth crashes with the early Linux3.14 rc1 that I tried, blocking my disk decryption system so I have yet to test the new kernel. With Mesa 10.2 but reverting to Xserver 1.14, I got back most of the regression but was still down 10-20%. That was the part that apparently turned out to by from hyper-z in my tests.

      I got essentialy identical performance using Mesa 10.1 or Mesa 10.2 with hyper-z force-enabled in Critter (only one Z value, it's a 2d game) , but in Scorched3d,

      R600_HYPERZ=1 scorched3d

      locked up the whole x server with Hyper-Z and Mesa 10.2, with either version of X. I checked the exact same code with Mesa 10.1, no problems at all in Scorched3d.

      I am guessing the issue with the new X server relates either to the DRI 3 changeover or to the rewrite of the GLX system referred to in the changelogs.
      You can do a git bisect to find out which commit introduced the regression.

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      • #43
        A git bisect is beyond my skills

        Originally posted by AnAkIn View Post
        You can do a git bisect to find out which commit introduced the regression.
        Sorry about that, but I would not know the slightest thing about doing that. Surely someone out there does,
        given how many people use Mesa and X.

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        • #44
          Originally posted by Luke View Post
          Sorry about that, but I would not know the slightest thing about doing that. Surely someone out there does,
          given how many people use Mesa and X.
          Here's an excellent how-to for using the git bisect commands to find the commit which caused the regression. Fairly simple, really:
          http://git-scm.com/book/en/Git-Tools-Debugging-with-Git

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          • #45
            I've never even compiled Mesa from source

            Originally posted by andyprough View Post
            Here's an excellent how-to for using the git bisect commands to find the commit which caused the regression. Fairly simple, really:
            http://git-scm.com/book/en/Git-Tools-Debugging-with-Git
            Not simple from where I sit. I've compiled Audacity and Kdenlive from source, but never Mesa. I don't have the bandwidth at home to be pulling a lot of build dependancies, have to get system
            updates on the road, etc. Not very likely I wll be the one to do this-especially when Mesa 10.1 works just fine for me and taking on a big new project is not something I can do right now.
            Last edited by Luke; 03-03-2014, 11:51 PM.

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            • #46
              was this fixed in 3.14-rc6? I remember there was a bug report, but I can't find it :/
              Last edited by asdfblah; 03-10-2014, 12:58 PM.

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              • #47
                Regressions I found were not in the kernel

                Originally posted by asdfblah View Post
                was this fixed in 3.14-rc6? I remember there was a bug report, but I can't find it :/
                I was able to roll back the regressions by rolling back Xorg and Mesa. Xorg was the worst offender, in Mesa only the hyper-Z issue caused a slowdown but Scorched3d locks up on the HD6750 if you use hyper-Z with Mesa 10.2. Works fine with Mesa 10.1, and both work fine with hyper-Z on the Radeon HD5570.

                I first installed the 3.14 kernels after this point, at first could not use them because of a GPU power management firmware bug. Last week a new Lnux-firmware package fixed that, and I found no performance regressions between the 3.13 and 3.14 kernels on my systems with the use cases I have. All the problems were in Mesa and X.

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                • #48
                  Originally posted by Luke View Post
                  I was able to roll back the regressions by rolling back Xorg and Mesa. Xorg was the worst offender, in Mesa only the hyper-Z issue caused a slowdown but Scorched3d locks up on the HD6750 if you use hyper-Z with Mesa 10.2. Works fine with Mesa 10.1, and both work fine with hyper-Z on the Radeon HD5570.

                  I first installed the 3.14 kernels after this point, at first could not use them because of a GPU power management firmware bug. Last week a new Lnux-firmware package fixed that, and I found no performance regressions between the 3.13 and 3.14 kernels on my systems with the use cases I have. All the problems were in Mesa and X.
                  Yes? I thought the problem was in the kernel...

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                  • #49
                    Not what I have seen

                    Originally posted by asdfblah View Post
                    Yes? I thought the problem was in the kernel...
                    I've heard reports of a regressio there but never seen it. The X regression is so bad I had to pin Xorg in the machine I use for games

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                    • #50
                      Originally posted by Luke View Post
                      I've heard reports of a regressio there but never seen it. The X regression is so bad I had to pin Xorg in the machine I use for games
                      Well, it was this thread: http://www.phoronix.com/forums/showt...untu-14-04-LTS
                      I don't get it, does it affect ATI/AMD every card, or just cards < r600 ?

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