Kris Kennaway wrote:
On Tue, Apr 17, 2007 at 01:12:06PM +0200, 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?
Someone else pointed this out to me, to be honest I didn't get that
far in your email after noticing the big blunder of leaving debugging
enabled :)
I agree that the different speed negotiation is a likely potential
cause of poor performance as well, but it really doesn't make sense to
be making performance comparisons when one system has all possible
debugging enabled and the other has no debugging enabled.
Kris
The difference in bus speed is hardly perceptible for a single target.
U320 does reduce the per-command latency by a good deal, but for large
I/O transfers it'll mostly be in the noise.
Scott
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