Subject: Re: New IDE controller.
To: Roine Thunberg <artee@garderoben.ath.cx>
From: Richard Rauch <rauch@rice.edu>
List: port-i386
Date: 02/23/2002 23:45:04
 [...]
> > The number of seeks should be closer to 1000 or 1500 per second, I
> > believe.
> >
> >
> > Again, it *flies* in single-user mode.
> >
>
> dumb question... DMA?

Sorry, I thought that I posted this information before:

 /~~~ dmesg

pciide0 at pci0 dev 7 function 1: VIA Tech VT82C586A IDE Controller (rev. 0x10)
pciide0: bus-master DMA support present
pciide0: primary channel configured to compatibility mode
wd0 at pciide0 channel 0 drive 0: <Maxtor 52049H4>
wd0: drive supports 16-sector pio transfers, lba addressing
wd0: 19541 MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 40020624 sectors
wd0: 32-bit data port
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 5
pciide0: primary channel interrupting at irq 14
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2 (using DMA data transfers)

 \___ dmesg

(With a different controller, I get UDMA 5 from the drive I believe; I'm
not sure why it's only in UDMA 2, here...I thought that it was previously
reporting a higher UDMA mode.  Strange...  But, I think, not my primary
concern.  Doing a dd read from the raw device is about 1/100 what it
should be.)


> but that shouln't matter if it runs better in single mode.

I wouldn't think so.  Besides, the scale of the performance (and on
*seeks*) makes DMA an unlikely explanation.

  ``I probably don't know what I'm talking about.'' --rauch@math.rice.edu