Subject: Re: new SATA controller/drive _very_ slow (PIO mode 0)
To: None <>
From: Jim Bernard <>
List: current-users
Date: 12/19/2007 05:42:36
On Tue, Dec 18, 2007 at 11:40:08PM -0500, George Georgalis wrote:
> pdcsata0 at pci4 dev 13 function 0
> pdcsata0: Promise PDC40718 SATA300 controller (rev. 0x02)
> pdcsata0: interrupting at ioapic0 pin 17 (irq 11)
> pdcsata0: bus-master DMA support present

  The VIA card looks equally promising at that point:

viaide1 at pci0 dev 11 function 0
viaide1: VIA Technologies VT6421 Serial RAID Controller (rev. 0x50)
viaide1: bus-master DMA support present
viaide1: using irq 10 for native-PCI interrupt
viaide1 port 0: device present, speed: 1.5Gb/s

It's when the disk is configured that the mode is downgraded:

wd2 at atabus2 drive 0: <WDC WD5000AAKS-00YGA0>
wd2: drive supports 16-sector PIO transfers, LBA48 addressing
wd2: 465 GB, 969021 cyl, 16 head, 63 sec, 512 bytes/sect x 976773168 sectors
wd2(viaide1:0:0): using PIO mode 0

  Does it actually use DMA for the disk(s)?