FreeBSD 5.3 I/O Performance / Linux 2.6.10 | Continued Discussion

Arne Wörner arne_woerner at
Thu Feb 3 10:09:39 PST 2005

--- Robert Watson <rwatson at> wrote:
> On Thu, 3 Feb 2005, Arne WXrner wrote:
> > I just tested R5.1 with a
> >   time -c "dd if=/dev/zero of=a bs=64k count=1000 ; fsync a" 
> > and it was 4 or about 4 times fast than with R5.3. 
> > 
> > Is it smart to start looking for regressive changes in
> > sys/dev/ata or in /sys/kern? 
> > 
> > I mean: Did somebody see this phaenomenon on a SCSI disc, too?
> I'd start by checking to see if the driver/hardware have
> negotiated the same ATA DMA paramaters or not.
> Specifically, what UDMA level (etc) was negotiated).
Hmm. I just know, how to find out the UDMA level:
They are for both devices at that ATA channel: UDMA100
ad0: 38166MB <ST340015A> [77545/16/63] at ata0-master UDMA100
ad1: 152627MB <SAMSUNG SP1604N> [310101/16/63] at ata0-slave

R5.3 behaves not worse, when I drop ad0 to UDMA66 with atacontrol.


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