Difference between 6.2 and 7.0 Adaptec 39320D - 7.0 performing less

Gelsema, P (Patrick) - FreeBSD freebsd at superhero.nl
Tue Apr 17 11:38:32 UTC 2007

On Tue, April 17, 2007 01:03, Kris Kennaway wrote:
> On Mon, Apr 16, 2007 at 10:47:24PM +0200, Gelsema, P (Patrick) wrote:
>> Goodevening lists,
>> I am toying with Freebsd 7 to see if it will and how it runs on my new
>> Asus
>> M2N mainboard. One of the things I noticed is that when running
>> 7.0-Current-200704 the throughput of the SCSI drive seems halved. When
>> running 6.2 throughput is doubled/normal.
>> Throughput is measured with the following command.
>> dd if=/dev/zero of=/usr/test
>> where /usr resides on da0s1f
>> On 7.0 I get about 33MB/sec
>> On 6.2 I get about 69Mb/sec
>> I did not make any changes, installation is fresh from CD with Minimal
>> as
>> distribution.
> Apparently you weren't paying attention during boot, because 7.0 ships
> with heavy debugging options enabled, and tells you about it up front:
>      "WARNING: WITNESS option enabled, expect reduced performance.\n";
> Recompile your kernel with debugging options disabled before making
> performance comparisons.
> Kris

Ok, what you are saying makes sense. I did see the warnings and the bits
in the kernel config. The thing that triggered me was that when paying
attention during boot the SCSI Disk was detected as only 160.00MB/s
instead of the expected 320.00MB/s. The detection of devices is not
subject to debugging, is it?

Excerpts from log.

Freebsd 7
da0: <SEAGATE ST336753LW HPS2> Fixed Direct Access SCSI-3 device
da0: 160.000MB/s transfers (80.000MHz DT, offset 63, 16 bit)
da0: Command Queueing Enabled

Freebsd 6.2
da0: <SEAGATE ST336753LW HPS2> Fixed Direct Access SCSI-3 device
da0: 320.000MB/s transfers (160.000MHz DT, offset 63, 16 bit), Tagged
Queueing Enabled



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