[vdr] PCI fun (RGB/PAL over VGA at variable frame rate)

Gavin Hamill gdh at acentral.co.uk
Sun Aug 17 17:31:58 CEST 2008


On Sun, 2008-08-17 at 03:41 +0200, Artur Skawina wrote:

> PCI in general should be perfectly fine, for SDTV at least. 
> While displaying SDTV (vdrsxfe) I see ~20% cpu use for X on AGP, ~44% on PCI
> (same machine, different heads, AGP is MGA450, PCI is MGA200).

Yes, 40% CPU has been what I've seen. The problem is that it's system
CPU usage rather than userspace. Due to the critical timing nature of
the patches, they need to have nearly the whole machine to themselves,
thus DMA PCI overhead causing things to be a 'a bit sticky' is just too
much :/

> You could probably do some setpci tweaks to improve PCI throughput, but
> I doubt the gain would be enough (I'd expect 10% improvement or so).

I did try to twiddle with setting PCI latency timers but it had no
measurable effect..

Cheers,
Gavin.





More information about the vdr mailing list