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

Clemens Eisserer linuxhippy at
Mon Jul 10 07:27:01 PDT 2006

Hi Owen,

> It's very likely that the speedup here is simply due to variations as
> to what gets put into video memory and what into system memory.

I talked to nvidia driver developers about this issue and they told me
that this is the case (I also saw a lot of time spent in malloc
routines). This initially brought me to work in this a bit.
They said that they'll include an option to disable pixmap-punting,
however then a lot fo time will be spent inside the driver and the GPU
for allocating the pixmap in VRAM.
Its quite common that such surface-puntnig optimizations are in the
drivers - I would not wonder if ATI would do the same in their
propietary drivers.
Thats why I would be really interrested about results on ATI chips
(open and proprietary drivers) as well as onboard gpus.

But when keeping in mind that an expose should happen in not more than
50-75ms I still think allocating and deallocating 12mb of pimaps
(gftp) for a single expose is simply too expensive. Also, many
double-buffered toolkits do it the same way - Java Swing does not even
release the pixmaps if windows are minimized.

I would like to see a design which maybe would allow different
approaches (maybe based on user descisions), so everybody would have
the choice.

lg Clemens

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