On Thu, 11 Jul 2019, user...@yahoo.com wrote:

> 8) Xorg_sid_fbdev.log    : Xorg log file for test (3)
> 9) Xorg_sid_mach64.log   : Xorg log file for test (4)

Thanks for sending these results.

Unfortunately these SID test results might be skewed because the X server 
is continually logging "dbus-core: error connecting to system bus" at 10 
times per second. So if you're using single-user mode, you may have to 
start up dbus first.

Anyway, if we assume that the measurements aren't skewed, we see that the 
majority of the the x11perf measurements have regressed (for fbdev).

But note that, unlike mach64, fbdev performance depends on both the kernel 
fbdev driver and the x server fbdev driver. These test results were taken 
from different kernels.

When you make fbdev measurements, you should use the same kernel binary 
and kernel parameters for each test. In the previous fbdev test, I think 
you used a kernel that I built from Debian's .config --

[   236.387] Current Operating System: Linux mac-server 4.19.56-debian-pmac #1 
Wed Jul 3 20:08:58 AEST 2019 ppc
[   236.387] Kernel command line: root=/dev/sda11 single ignore_loglevel 
printk.time console=ttyS0,9600n8 video=ofonly

I think this was a good choice.

Please also capture the complete console log if convenient.

> 
> c) The glxgears tests are included for reference.  Those results give a 
> better picture of the overall slowdown in X11 graphics from Debian 8.11 
> to Debian sid.  The slowdown is most easily seen when running in 
> multiuser mode with Xfce (see particularly the last two tests in the 
> file), where the glxgears FPS is about 14.1 FPS in Debian 8.11 but only 
> 4.7 FPS in Debian sid.  So perhaps there are some interrelated issues 
> with Xorg and Xfce and/or mesa-utils, especially since glxgears has 
> intermittent segmentation and illegal instruction errors (only in sid).
> 

Unfortunately, glxgears doesn't reflect the "overall slowdown". More data 
is always good, however, the x11perf microbenchmarks are more tightly 
focused.

> d) It takes approximately three seconds to open an xfce4-terminal in
> Debian 8.11, six seconds in Debian sid.
> 

A 50% slowdown is serious. But it may not be caused by Xorg.

If you were to patch the X server, or change the xorg.conf (e.g. shadowfb) 
or downgrade all of the X server packages, and if this fixed the slowdown, 
then that would prove that the regression was in the X server.

But it seems that you already have x11perf results which demonstrate an X 
server performance regression. Fixing this may or may not fix the Xfce 
slowdown. It remains to be seen.

> e) Moving and resizing windows might be faster in all versions of Debian 
> if the default setting would be to highlight only the window borders 
> while moving or resizing, instead of including the window contents. This 
> is probably an Xfce setting.
> 

Right. If Xfce doesn't offer this feature, there are certainly other 
window managers that do offer this.

If this is an Xfce bug, you'll need to file a bug report against that 
package, in order to reach the relevant developers.

-- 

> -Stan Johnson
>  user...@yahoo.com
> 

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