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Red Hat Recommends Disabling The Intel Linux Graphics Driver Over Hardware Flaw

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  • #21
    Originally posted by polarathene View Post
    Michael tested a Whiskey Lake for Gen9 to see if there was any power regression as a result despite the minimal performance regression for Gen9 graphics, and found no change in power draw, unless he didn't test it right(eg tested on at load rather than idle..)
    Hm, which exactly case are we talking about? I was talking about the mitigation described in the linked article, i. e. blacklisting the i915 kernel driver. Applying the proper mitigation for gen8/9 doesn't seem to carry a significant penalty indeed.

    Originally posted by polarathene View Post
    As for the RC6, how to I verify that? My Comet Lake seems to report RC6 in PowerTop, but perhaps I'm looking at the wrong place, don't know too much about such yet. Not sure that I can test on older kernels either as 4.19 didn't seem to boot from install media(live usb) with such
    I wasn't talking about 4.19... Anyhow, to check rc6 residency you can either look into powertop or run turbostat with something like this:

    Code:
    sudo turbostat -S -s GFX%C0,GFX%rc6,Busy%,Pkg%pc2,Pkg%pc3,Pkg%pc6,Pkg%pc7,Pkg%pc8,Pkg%pc9,Pk%pc10
    Then look at GFX%rc6 and (as an integral measure of how good is your power saving) Pkg%pc8 to pc10.

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    • #22
      Originally posted by intelfx View Post
      Hm, which exactly case are we talking about?
      Sorry there was a similar article that I mixed your response up with, which had the benches for performance regression but lacked impact on battery which a user claimed went up a fair bit at idle prior to the patch.

      Originally posted by intelfx View Post
      I wasn't talking about 4.19...
      I know, I mentioned it because it's the LTS prior to 5.4, so most install media ships with it by default. On Manjaro which I use I'll have to check but I think kernels that aren't LTS get EOLed so using kernels inbetween would require getting source and compiling my own I guess as my Comet Lake doesn't seem like it boots with 4.19 kernel for whatever reason(could just be their stupid hardware detection getting in the way and assigning a bad driver or something since the IDs for Comet Lake would be missing in the kernel?).


      Originally posted by intelfx View Post
      Anyhow, to check rc6 residency you can either look into powertop or run turbostat with something like this:

      Code:
      sudo turbostat -S -s GFX%C0,GFX%rc6,Busy%,Pkg%pc2,Pkg%pc3,Pkg%pc6,Pkg%pc7,Pkg%pc8,Pkg%pc9,Pk%pc10
      Then look at GFX%rc6 and (as an integral measure of how good is your power saving) Pkg%pc8 to pc10.
      I'll give that a go soon, thanks. All I remember is was seeing rc6 in the idle stats tab I think for powertop and it had the bulk of the % assigned to it.

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      • #23
        Originally posted by polarathene View Post
        All I remember is was seeing rc6 in the idle stats tab I think for powertop and it had the bulk of the % assigned to it.
        Hm, which exactly CPU and kernel version was this?

        My i7-8550U (Kaby Lake) is definitely broken with 5.4.x, see here: https://gitlab.freedesktop.org/drm/intel/issues/614
        Last edited by intelfx; 01-17-2020, 12:22 PM.

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        • #24
          Originally posted by starshipeleven View Post
          Does Intel Graphics even run Crysis? I'm pretty sure they still can't.
          Au contraire, I was fiddling around with my laptop (sporting an Intel 8250U processor with 620 graphics) and with DXVK 1.51 Crysis is very playable and without the awful "flashing grass" issue that has dogged Intel graphics on Crysis before. Of course this is at 1366x768 and high settings. Still the frame rates were, as I recall, in the 40-50 FPS range.

          The flashing grass issue is still present when not using DXVK though and it really makes the gaming experience unpleasant.

          Mageia 7, wine 5.0 RC5, Mesa 19.2.3, llvm 8.0. kernel 5.4.10.

          I don't have anything useful to add but if you're stuck in an elevator with your Intel laptop and your GOG collection, you can play Crysis.

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          • #25
            Originally posted by intelfx View Post

            Hm, which exactly CPU and kernel version was this?

            My i7-8550U (Kaby Lake) is definitely broken with 5.4.x, see here: https://gitlab.freedesktop.org/drm/intel/issues/614
            i3-10110U (Comet Lake) UHD620 graphics. Running the current stable Manjaro KDE ISO(18.1.5 with kernel: 5.4.6-2-MANJARO) via USB, powertop shows in the "Idle stats" section 2nd column under "GPU":

            Code:
            Powered On 21.8%
            RC6                78.2%
            RC6p                0.0%
            RC6pp              0.0%
            While typing that those two values changed to 11.7% / 88.3%, and then 18.6% / 81.4%, and once more to 36 / 64 and shortly after back to the 20 / 80 range, and after moving the mouse around on elements a bit to 95 / 4, I tried moving the mouse on/off a UI element to spam it's hover state on/off and that gave a 100 / 0. So it seems to be working?
            Last edited by polarathene; 01-18-2020, 03:14 AM.

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