Re: FreeBSD 5.3b7and poor ata performance

> Date: Thu, 21 Oct 2004 08:40:57 -0700
> From: Kris Kennaway <kris_at_obsecurity.org>
> Sender: owner-freebsd-current_at_freebsd.org
> 
> On Thu, Oct 21, 2004 at 09:35:12AM +0200, fandino wrote:
> > Mike Tancsa wrote:
> > >Its strange that you do not see any difference in speed when reading
> > >from the device directly vs a file ? I see quite a difference in my
> > >setup on a RELENG_5 box and not so much a difference on a RELENG_4 box.
> > >Perhaps as someone suggested, the GEOM layer ?
> > >
> > >e.g. create a file with junk larger than your RAM. (the machine below
> > >has 256M)
> >
> > -- same mobo and same disks --
> >
> > OpenBSD 3.5:
> >
> > dd if=3D/mnt/aa of=3D/dev/null bs=3D1024k count=3D1024
> > 1024+0 records in
> > 1024+0 records out
> > 1073741824 bytes transferred in 18.743 secs (57287584 bytes/sec)
> >
> >
> > FreeBSD 5.3rc1:
> >
> > # dd if=3D/mnt/aa of=3D/dev/null bs=3D1024k count=3D1024
> > 1024+0 records in
> > 1024+0 records out
> > 1073741824 bytes transferred in 42.215597 secs (25434719 bytes/sec)
> 
> BTW, others have asked that you not use dd as your "benchmark",
> because it's not benchmarking anything relevant for real-world use of
> the disk.

While it is not typical of many "real-world" uses, I back up my laptop
by copying the disk with dd(1). It used to take me about 40 minutes with
V4. Now it takes just over an hour. This 25 minutes lost every day is a
very real part of my world.

I also bothers me to see this significant deterioration on what appears
to be a VERY simple disk activity. I'd like to benchmark buildworld, but
doing that with different versions is not so easy. I might try building
jdk. That is very "real-world".
-- 
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