Re: [AD] SF.net SVN: alleg:[13312] allegro/branches/4.9

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On 25 April 2010 11:40, Thomas Fjellstrom <tfjellstrom@xxxxxxxxxx> wrote:
> On April 24, 2010, Peter Wang wrote:
>> On 25 April 2010 10:39, Thomas Fjellstrom <tfjellstrom@xxxxxxxxxx> wrote:
>> > I'm not sure I can see how xrandr info fetching can cause any serious
>> > cpu use, and even then audio just shouldn't stutter these days (least
>> > I find it hard to get audio to stutter even when both my cores are
>> > pegged, amarok and X/KDE can be locked up solid, but the audio will
>> > still play).
>>
>> I think it has to do with analogue VGA connectors.  IIRC the flickering
>> happens when the analogue outputs are used (even as secondary monitors).
>>  Maybe the information it needs is not readily available so it uses some
>> brute force probing technique on those monitors.
>
> I haven't noticed such a problem on any of my systems (intel gma vs radeon
> vs gforce). So I'm not sure what's going on.

It doesn't seem to be always reproduceable (e.g. I can't reproduce it today!).
If you search for "XRRGetScreenResources flicker" you'll find quite a lot of
reports about it.

Here is a relevant thread and quote:
http://thread.gmane.org/gmane.comp.freedesktop.xorg/30567

    "XRRGetScreenResources is an expensive call.  Always.  If gtk is calling
    it on every app startup they're absolutely insane."

although patches to mitigate the problem are proposed later in the thread.
I don't know if something like that is in the latest xorg. But...

Looking at GTK, it looks like they switched to relying on xinerama information
for a while, then restored randr _1.3_ support, using a call to
XRRGetScreenResourcesCurrent instead of XRRGetScreenResources.
http://svn.gnome.org/viewvc/gtk%2B/trunk/gdk/x11/gdkscreen-x11.c?view=log

Indeed, although I can't reproduce the flicking/stuttering today,
with XRRGetScreenResourcesCurrent Allegro programs start up quicker.
With XRRGetScreenResources I at least get a delay of maybe half a second.

So *Current looks to be the solution.

Peter




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