Bug#542701: xserver-xorg-video-intel: Very slow 2D performance on one screen of dual display until after switch to console VT and back.
Excerpts from Thomas Vaughan's message of Thu Sep 03 16:54:13 -0700 2009:
> On Thu, Sep 3, 2009 at 12:02 PM, Carl Worth<cworth@cworth.org> wrote:
> > You've got a very mysterious bug.
>
> Well, at least I have a reliable work-around.
Yes, that is nice to have.
> The output of 'xrandr --verbose' was identical from before to after the
> VT switch. I diffed the results and got null output. I'll attach one
> of the output files.
I'm not actually all that surprised there, (even if it was some weird
RandR thing, the output from xrandr is not too verbose).
> Moreover, I've done most of my testing by just killing the display
> manager and starting X with xinit, and then doing 'twm &' at the shell
> prompt in xterm.
OK. So that eliminates the desktop environment as a cause.
> By the way, do you have access to hardware on which this anomaly can be
> reproduced?
Hmm... are you suggesting that I should perhaps ask for more giant LCD
panels. I think I like the way you think. :-)
Seriously, though, I will try to setup such an environment and see if
I can replicate the behavior.
> By the way, I don't mind grabbing the relevant source and building for
> debug output, if that would be of any help. I just need to know how to
> turn on the relevant output or else where to stick some printf()s.
If you're interesting in building things, one thing you might do is to
build a recent kernel and use kernel modesetting, (load the i915
module with the option "modeset=1" either on the modprobe command line
or by putting "i915 modeset=1" into /etc/modules). It would be
interesting to hear if the behavior is identical with a KMS setup.
-Carl
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