Graphics Performance

Rask Ingemann Lambertsen rask at
Sat Apr 4 15:33:26 CEST 2009

On Fri, Apr 03, 2009 at 09:14:16PM +0100, Ian Stirling wrote:
> Iain B. FIndleton wrote:

> > I 
> > wonder what the issue is in moving the frame buffer data? At the speeds 
> > available on the FR, moving 640 x 480 x 2 = 614,400 bytes from memory to 
> > a video buffer at 30 Hz needs about 18 MB/sec.
> > 
> > What is the bandwidth for memory moves?
> About 6-8 or so - with 100% CPU utilisation

   There are four DMA channels in the s3c422b, so you shouldn't use the CPU
for straight memcpy() of such large blocks. The kernel doesn't yet support
mem->mem DMA transfers, but I'm working on that to use it in the glamo SD
card driver.

Rask Ingemann Lambertsen
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