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Ondemand governor dramatically slows down mesa perfomance

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  • Ondemand governor dramatically slows down mesa perfomance

    With kernel >=3.8 and Mesa 9.2 and ondemand governor cpu frequency don't change in 3d.

    ondemand performance
    glxgears 3400 6200
    openarena 100 125
    lightsmark 240 340

    can somebody confirm this?

  • #2
    Kernel 3.7.10 and Mesa 9.1.1, but I see the same.

    glxgears pegs one core, but the frequency stays on low.


    Used this to check: watch -d -n 1 "grep MHz /proc/cpuinfo | uniq"

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    • #3
      Originally posted by curaga View Post
      Kernel 3.7.10 and Mesa 9.1.1, but I see the same.

      glxgears pegs one core, but the frequency stays on low.


      Used this to check: watch -d -n 1 "grep MHz /proc/cpuinfo | uniq"
      cpupower frequency-set -g performance

      Increases the FPS?

      Comment


      • #4
        Yes, the performance governor about doubles the fps.

        Comment


        • #5
          Originally posted by Pontostroy View Post
          With kernel >=3.8 and Mesa 9.2 and ondemand governor cpu frequency don't change in 3d.

          ondemand performance
          glxgears 3400 6200
          openarena 100 125
          lightsmark 240 340

          can somebody confirm this?

          works fine here

          just noticed that the conservative governor that I had used all the time didn't clock up all that much at all

          glxgears always stayed around 2500 - now with ondemand it goes up to 3800

          that's with a 5850

          what card is that on your side ?

          screen resolution is 1920x1080 here


          had to use R600_DEBUG=sb vblank_mode=0 glxgears to use its full potential

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          • #6
            Yes this is well known, and I always warn people for this on IRC
            when gaming always use performance governor it's +33-50% fps difference in many scenes
            (and get a fast cpu per core also 3-4+ GHz )

            ideally you would bind your game to 1 core (and mesa to another?) and only put that core into performance mode.

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            • #7
              Originally posted by pheldens View Post
              Yes this is well known, and I always warn people for this on IRC
              when gaming always use performance governor it's +33-50% fps difference in many scenes
              (and get a fast cpu per core also 3-4+ GHz )

              ideally you would bind your game to 1 core (and mesa to another?) and only put that core into performance mode.
              had the same issue occuring to me a few days ago

              so ondemand isn't working very reliably (it didn't clock the cpu up)


              you could also try conservative governor a try

              or try tweaking conservative & ondemand governor to clock up more aggressively

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              • #8
                I think it makes more sense to just use the performance governor all the time when running on a desktop, as you won't save that much power from using ondemand anyway. And on a laptop you can use laptop-mode-tools to set ondemand/conservative when on battery, and have it force to performance when AC power is supplied.

                Alternatively, you could setup up a script to force performance whenever you play a demanding game.

                Comment


                • #9
                  Well, it depends on how much is much. This desktop here has a 60W difference when running idle vs running with all cores full.

                  Comment


                  • #10
                    Originally posted by curaga View Post
                    Well, it depends on how much is much. This desktop here has a 60W difference when running idle vs running with all cores full.
                    Yeah, that's pretty substantial. I remember testing it a long time back and it was more like 10W difference or something like that. But it probably varies by CPU and the scaling implementation; they have both probably gotten a lot better.

                    I should test my current systems to check for myself.

                    Comment


                    • #11
                      yes the powersaving is worth it, while doing simple office work, or when leaving pc running
                      so you're best of manually toggling the governor. all or nothing

                      Comment


                      • #12
                        For those of us running Ubuntu and using Unity, installing indicator-cpufreq provides easy access to all of the governors, and also individual p-states.

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                        • #13
                          A couple of things worth noting:
                          - glxgears is not a benchmark. It does a pittance of work on both the CPU and GPU...so basically all you're measuring is how fast you can swap frames. That's not representative of really anything you're going to do. If you're playing a game, you're going to spend CPU time on game logic, and GPU time drawing a bunch of stuff. Even if you're just browsing the web or reading PDFs, you're probably going to do more than glxgears.
                          - You need to use vblank_mode=0, otherwise you'll be locked at 60 fps.
                          Free Software Developer .:. Mesa and Xorg
                          Opinions expressed in these forum posts are my own.

                          Comment


                          • #14
                            you guys can try experimenting with the ondemand governor and its trigger values until it ramps up - for me it's 50:

                            echo 50 > /sys/devices/system/cpu/cpufreq/ondemand/up_threshold


                            seems like the CPUs became too powerful for the value of 95 so it stays downclocked all the time

                            strangely this affects output of the GPU a lot

                            so with the old settings glxgears was between 2600-2900

                            now it's between 3800 and roughly 4100 (4500 seems to be the max with performance governor/without throttle)


                            playback of youtube videos also significantly improved with this setting

                            Comment


                            • #15
                              Originally posted by kernelOfTruth View Post
                              strangely this affects output of the GPU a lot
                              It's not strange. The CPU feeds the GPU. gears doesn't stress the GPU at all. The faster you can feed the GPU, the faster gears will perform. See Kayden's comment.

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