Disk performance under CURRENT

[Kevin Oberman]

> Date: Sat, 22 May 2004 09:36:18 -0600
> From: Scott Long <scottl at freebsd.org>
> 
> Kevin Oberman wrote:
> > I just ran test of disk writing performance under V4 (STABLE) and V5
> > (CURRENT) and was surprised at the difference.
> > 
> > The test was simple and not at all rigorous. Just a dd bs=256k
> > if=/dev/zero of=/dev/ad2. This is about the simplest way of dealing with
> > a disk. No file system or anything else. Just raw data to the device.
> > 
> > Under STABLE, I get an average of 25 MB/sec to the disk. Under CURRENT,
> > it drops to 15 MB/sec. I did this because I had noted that it was now
> > taking over an hour to backup my system disk (40 GB) when it was only
> > taking 40 minutes when I was running V4.6. The STABLE system was built
> > yesterday. The CURRENT system last Sunday.
> > 
> > Any idea why this is so much slower? It looks to me like it must be in
> > either geom or the disk driver.
> 
> Btw, before we run off and dig into performance work here, can you send
> the output of the following from your test machine:
> 
> sysctl debug.witness_watch

Sorry, but I've been off-line for a while on travel. And my wireless
card died. :-(

In any case, by kernel is built without witness, so I get sysctl:
unknown oid 'debug.witness_watch'. The system is a UP P4-M and not
running APIC. No INVARIANTS, either.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634