On Mon, 20 Dec 2004 14:59:19 -0500
Chapman Flack <chap0@cs.purdue.edu> wrote:

> I have what may be a simple question (or a few):
> 
> In this configuration, what method of transfer is being used to get data
> from the DVD to memory?  Not bus-master dma, I take it, so what happens
> instead?  How much is the cpu involved?
> 
> mainbus0 (root)
> cpu0 at mainbus0: (uniprocessor)
> cpu0: Intel Mobile Pentium II (686-class), 397.07 MHz, id 0x66a
> pci0 at mainbus0 bus 0: configuration mode 1
> pci0: i/o space, memory space enabled, rd/line, rd/mult, wr/inv ok
> pciide0 at pci0 dev 7 function 1
> pciide0: Intel 82371AB IDE controller (PIIX4) (rev. 0x01)
> pciide0: bus-master DMA support present, but unused (no driver support)
> atabus1 at pciide0 channel 1
> atapibus0 at atabus1: 2 targets
> cd0 at atapibus0 drive 0: <TOSHIBA DVD-ROM SD-R6112, 14EM708962, 1031> cdrom removable
> cd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 2 (Ultra/33)
> 
> Reason for the question: ogle playing a dvd hiccups frequently.  The hiccups
> seem well coordinated with the drive access light, as if ogle isn't able to
> keep buffered video and sound going while it gets more bits from the disk.
> Does it seem likely that bus-master dma could improve that, or is this
> system probably just too slow (400MHz PII, 512MB PC100 memory) for playing
> dvds?
> 
> If bus-master support might help, how hard is it to add support?
> I assume there is driver support for it in other chipsets, and I'd just
> have to work out the specifics for mine?  Where should I start?
> 
> More off the dma topic, if anyone knows of simple tweaks I haven't thought
> of that might help for dvd playing, I'd love to hear them.  Btw the
> XFree 4.4 driver doesn't correctly support hardware block copy on my
> NeoMagic 256ZX, which means I have to turn that feature off, which means
> that much more cpu overhead just for the video output - I'm sure there'd be
> a big improvement if I could get that driver working but what can you do when
> there's no way to get the chip docs?   :(
> 
> -Chap
> 
> 
Hi,

Did you try the piixide(4) driver? It should be present in the GENERIC kernel.
I assume you're using NetBSD 2.0 as you didn't indicate otherwise.
PIO mode uses a large chunk of CPU.
On the video performance issue I'd give MPlayer with the DGA driver a shot.

-Tobias