gistfile1.txt

  services.xserver = {
    videoDrivers = [ "ati" ];
    deviceSection = ''
      # We don't need TearFree to avoid tearing in Chrome and mpv; TearFree also
      # has the disadvantage of making switches to text VTs take 2 seconds.
      #Option "TearFree" "on"

      # Use exa because glamor causes subtle but visible triangular tearing when
      # used without TearFree.
      Option "AccelMethod" "exa"

      # DRI3 is not enabled by default on my Radeon HD 6470M
      # https://en.wikipedia.org/wiki/Direct_Rendering_Infrastructure#DRI3
      # https://www.phoronix.com/scan.php?page=news_item&px=Ubuntu-16.04-Enable-DRI3
      Option "DRI" "3"
    '';
  };