On Thu, Nov 10, 2011 at 06:15:43PM +0100, Michel Dänzer wrote: > On Don, 2011-11-10 at 18:01 +0100, Michal Suchanek wrote: > > On 10 November 2011 17:46, Alex Deucher <alexdeuc...@gmail.com> wrote: > > > On Wed, Nov 9, 2011 at 12:36 PM, Iustin Pop <ius...@debian.org> wrote: > > >> > > >> The recent upgrade of xserver-xorg-video-radeon from 1:6.14.2-2 to > > >> 1:6.14.3-1 enabled ColorTiling for my card, which in turn caused a > > >> significant performance degradation in 2D (yes, I understand it should > > >> make 3D faster, but I didn't know it should slow down 2D applications). > > >> > > >> I'm using plain 2D environment (openbox, no compositing, anything) and > > >> plain xterm (bitmap fonts, no AA, etc.). The speed of display text has > > >> changed significantly enough that I can "see" my mutt refreshing the > > >> inbox and drawing the lines. > > > > > > Tiling will speed up all rendering (2D and 3D). However, it sounds > > > like you are using an environment that is mostly software rendering. > > > As such in order for the CPU to access tiled buffers, the GPU has to > > > copy them to a linear buffer before CPU can access it properly. > > > > FWIW I have color tiling enabled and have no speed issues in urxvt - > > TrueType fonts, AA enabled, etc. > > > > Unlike xterm urxvt (rxvt-unicode) uses some special font-rendering > > libraries, however. > > > > If I understand it correctly xterm would use the in-server bitmap font > > rendering which the X server can accelerate as much as it wants. > > Core bitmap fonts are completely unaccelerated so far with EXA. xterm > can also use Xft for font rendering via the -fa option though, which is > well accelerated.
Hi all, thanks for the replies. I've tested further and this seems to be a problem specific to xterm (and possibly other software? not sure how to test e.g. firefox's UI speed): Test file: ~20K lines. I've chosen the font sizes so as to have the same number of lines in full-screen. The timing is simply "time cat file". ColorTiling disabled: xterm -fn fixed: ~3.3s xterm -fa Mono -fs 8: ~8.6s rxvt-unicode -fn fixed: ~0.07s rxvt-unicode -fn xft:Mono:pixelsize=11: ~0.05s ColorTiling enabled: xterm -fn fixed: ~21s xterm -fa Mono -fs 8: ~7.8s rxvt-unicode -fn fixed: ~0.6s usually, sometimes ~0.1s?? rxvt-unicode -fn xft:Mono:pixelsize=11: ~0.05s So it seems to me that: a) whatever xterm does, it is very sub-optimal b) while xterm's -fa mode is indeed sped up by ColorTiling, it's still many times slower than with ColorTiling disabled and using core fonts c) also rxvt-unicode with core fonts is slowed down by color tiling, sometimes very much so (10x) Based on this I think this is mostly an xterm bug (-fa should/could be much faster), but I wonder if it also applies to other purely software 2D rendering. thanks, iustin
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