Gelsema, P (Patrick) - FreeBSD wrote:
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
Thanks,
The 39320D is a finicky card. I don't recall putting in the code that
would downshift the speed like this, but it wouldn't surprise me if it
is a side effect of the system going slower. Anyways, it sounds like
you're a good candidate/victim for the MPSAFE locking changes that I
just made to the SCSI layer and the ahc/ahd drivers. Would you mind
testing it out (just update to the latest 7-CURRENT sources) and let me
know how it works for you?
Scott
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