On Fri 15 Aug 2003 at 10:07:04 +0200, Jochen Kunz wrote:
> On 2003.08.15 07:59 Wilko Bulte wrote:
> 
> > But why aren't you using the onboard IDE controller?
> > Not the fastest in the world but..
> Not the festest is very kind. The CMD646 in the PWS has a broken DMA
> implementation. It can only transfer a few bytes per DMA, so it
> generates lots of interrupts. Someone posted benchmarks to this list a

and somehow in my PWS 433a, I still have to explicitly disallow the DMA
to/from the disk because it crashes the machine. Despite the workarounds
that should prevent that. So I guess that somehow my machine is more
broken than most of the others... and yes, the PIO is painfully slow.

Stangely enough, the DMA for the cdrom seems to work fine, on the same
controller.

> while ago. He compared a quite recent IDE disk connected to the onboard
> IDE controller and the same disk connected to the QLA1040 SCSI card via
> an IDE-SCSI bridge. 
> pure IDE: high CPU load, small disk throghput 
> IDE-SCSI: small CPU load, high disk throghput 
> 
> So I would recommend: Use a IDE disk with IDE-SCSI bridge on a SCSI
> adapter or a DMA capable IDE adapter. If SRM don't like the later

Would adding an IDE card help despite my DMA troubles, do you think?

wd*     at      pciide? channel ? flags 0xffc   # Use PIO mode 4, no DMA

pciide0 at pci0 dev 4 function 0: CMD Technology PCI0646 (rev. 0x01)
pciide0: bus-master DMA support present
pciide0: primary channel wired to compatibility mode
atapibus0 at pciide0 channel 0: 2 targets
cd0 at atapibus0 drive 0: <TOSHIBA CD-ROM XM-6102B, 7800327909, 1106> type 5 cdrom removable
cd0: 32-bit data port
cd0: drive supports PIO mode 3, DMA mode 2
pciide0: primary channel interrupting at isa irq 14
cd0(pciide0:0:0): using PIO mode 3, DMA mode 1 (using DMA data transfers)
pciide0: secondary channel wired to compatibility mode
wd0 at pciide0 channel 1 drive 0: <IBM-DPTA-353750>
wd0: drive supports 16-sector PIO transfers, LBA addressing
wd0: 35772 MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 73261440 sectors
wd0: 32-bit data port
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 4 (Ultra/66)
pciide0: secondary channel interrupting at isa irq 15
wd0(pciide0:1:0): using PIO mode 4

>        Jochen
-Olaf.
-- 
___ Olaf 'Rhialto' Seibert - rhialto@       -- "What good is a Ring of Power
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