From: "Jan Knutar" <[EMAIL PROTECTED]>
> On Wednesday 16 February 2005 19:17, HiNet wrote:
> 
> >       And X window use share memory to store the original
> > unscaled raw image. This is another headache. While frame rate gets
> > higher, or there are more than one video streams when using nvidia's
> > Video Blitter function, the CPU usage of X gets higher. Why? Shared
> > memory is not physically continuous and this is definitely one of the 
> > reasons. I've

Is it? No memory in user space is generally contiguous.
I'm not sure what causes the performance problems. Perhaps it is extra
copying of the video data, but that should not be necessary.

> > ever dreamed, some day there would be no X while using Video 
> > Overlay/Blitter.
> 
> That day came some time ago...

This seems a bit like to familiar X bashing...

What I fail to understand is why using shared memory for allowing
more than one process to access video data should be a performance
problem. Any buffer allocated by an application will in general not
consist of physically contiguous pages---that is why decent video
hardware should be able to read using scatter/gather.


--ms

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