> 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: +1 510 486-8634Received on Mon May 24 2004 - 07:19:20 UTC
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