David Kelly wrote:
On Dec 1, 2008, at 11:45 PM, Jan Mikkelsen wrote:
Replying to my own post ...
I have done a test on the same machine comparing 6.3-p1 to 7.1-PRE.
The performance is the expected ~6MB/s (because of the lack of cache)
on 6.3-p1, so the BIOS change doesn't seem to be at fault.
This seems to be a regression somewhere between 6.3 to 7.1. The Areca
driver is the same in 6.3 and 7.1, so the problem seems to be elsewhere.
I think this is more than just a "performance" problem. The
observations with gstat showing extremely high ms/w values (I have
seen them as high as 22000) makes it look like IO completion
interrupts are being lost.
Any suggestions on where to look next? Are there obvious candidates?
ATA maximum block transfer has dropped from 128k to 64k in 7.x. Am not
sure where the handle is to tweak it back up but has slowed peak thruput
on my Dell PE400SC. Can watch with "systat -v"
Interesting, thanks.
Worse, I have a stripped array of 2 drives that won't transfer more than
43k at a chunk because apparently the stripe metadata didn't align
nicely on 64k multiples.
I know the partitions start at 64kB multiples in my case. I did,
however, reduce the RAID-6 stripe size to 4kB (from 64kB) and that
improved things slightly, but the throughput on 7.1 is still slower by
about a factor of a about 6 (measured by untaring ~3GB across ~167k
files into a fresh filesystem). And on 7.1 the machine is unusable
during much of the time.
--
David Kelly N4HHE, [EMAIL PROTECTED]
========================================================================
Whom computers would destroy, they must first drive mad.
_______________________________________________
freebsd-stable@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-stable
To unsubscribe, send any mail to "[EMAIL PROTECTED]"
