[Xfce4-commits] r27940 - xfdesktop/trunk/src

[Olivier Fourdan]

Hi,

On Thu, Sep 25, 2008 at 7:27 AM, Brian Tarricone <kelnos at xfce.org> wrote:
> Author: kelnos
> Date: 2008-09-25 06:27:26 +0000 (Thu, 25 Sep 2008)
> New Revision: 27940
>
> Modified:
>   xfdesktop/trunk/src/xfce-desktop.c
> Log:
> double-buffer the desktop window again.
>
> i'm not entirely sure why we turned this off years and years ago.  it
> doesn't really impact performance (well, except for positively) or
> memory usage, and fixes a bunch of flicker issues i never got around to
> fixing.

The logic behind this was to work arround a major slowdown on some
NVidia card when double buffering was set.

My understanding of the issue is that the driver was allocating a huge
amount of memory for textures leaving a lot less for regular pixmaps.
By turning on double buffering on the desktop window, we basically
double the amount of pixmap used (one for the background picture
itself and other one for the buffer) causing the pixmaps to be stored
in main memory instead of video memory, causing the slowdown on
redraw.

Today, with compositing, the amount of pixmap memory used has
increased a lot so I guess the driver was modified to support larger
amount of pixmaps. Still, we may still have the problem with lower end
video cards, dunno.

Cheers,
Olivier.