Performance change from X in Fedora Core 4 to Fedora Core 5

Carsten Haitzler (The Rasterman) raster at
Thu Jul 13 06:18:35 PDT 2006

On Thu, 13 Jul 2006 13:48:48 +0100 Felix Bellaby <felix at>

> Carsten Haitzler wrote: 
> > > I based my gloomy forecast on my recent experience of trying to allocate
> > > and deallocate GLXPixmaps on nVidia hardware. Even when the new
> > > GLXPixmap references exactly the same Pixmap (which remains X allocated)
> > > this process takes longer than copying the Pixmap. I can only presume
> > > that this is a synchronisation problem, but I do not really know.
> > 
> > i suspect it is a sync and lock/unlokc/round trip performance issue. alloc
> > and de-alloc of 2d pixmaps inside of x is fast.
> I observed the problems in a indirect rendered compositor which held a
> server grab during all its drawing operations regardless of whether the
> GLXPixmaps were being realloced or not. The performance loss was
> spectacular, slowing glxgears and cairogears by 66% under the
> compositor.
> I would need to prototype some simple tests to gauge the effect in less
> unusual circumstances. It might be down to how well the nvidia GLX
> implementation copes inside a server grab. Otherwise a GL specific sync
> problem may be responsible.

holding a server grab! god damn - no wonder! :)

------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    raster at
Tokyo, Japan (東京 日本)

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