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[wlug] graphics speed

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Glenn Ramsey glenn@c...
Tue Sep 23 11:14:18 NZST 2003

Oliver Jones wrote:

>>I'm still boggled at anything over VNC being the fastest, though.  That's
>>just bizarre./
> The biggest problem historically with graphics has always been the 
> bandwidth between video memory and main memory.  Graphics are just plain 
> big and eat the data bandwidth something chronic.  So it is unsurprising 
> that VNC is faster than using a video card.  For 2 reasons:
> 1. Xvnc doesn't use the graphics hardware.  It renders to an in main 
> memory buffer.  No data is travelling on the AGP or PCI buses. 
> 2. The VNC protocol is a polling protocol that only refreshes the screen 
> when necessary and only transmits what has changed.  It is also 
> asynchronous to the video updates.  This means that only a fraction of 
> the video updates are being sent over the ethernet wire.

Running the app on the local xserver (xfree86 4.2.1) it appears to go 
just little bit faster than over vnc.  The chipset in this machine (the 
one you sold to me!) is S3 ProSavage and it uses the the vesa driver.


Glenn Ramsey <glenn@c...> 07 8627077

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