processes not getting fair share of available disk I/O (was: Re: TCP parameters and interpreting tcpdump output )

[Kris Kennaway]

On Wed, Nov 22, 2006 at 07:41:46PM +0000, Dieter wrote:

> > oad
> > > > > > have been trimmed from your email.
> > > > >=3D20
> > > > > In telnet window 1:
> > > > >=3D20
> > > > > cd /disk1/
> > > > > cp -ip very_big_file /disk2/bar/	(the workload)
> > > > >=3D20
> > > > > In telnet window 2:
> > > > >=3D20
> > > > > time ls /disk3/foo1/  (make sure time and ls are cached in memory)
> > > > > time ls /disk3/foo2/  (see timing numbers above)
> > > > > time ls /disk2/       (see timing numbers above)
> > > > >=3D20
> > > > > The /disk2/ directory is small, only contains 3 directories and .snap
> > > > >=3D20
> > > > > Would the cp into /disk2/bar/ lock the /disk2/ directory?
> > > >=20
> > > > It shouldn't do.
> > > >=20
> > > > What scheduler are you using?
> > >=20
> > > kern.sched.name: 4BSD
> > > kern.sched.quantum: 100000
> > > kern.sched.preemption: 1
> > 
> > OK, that's correct.  Can you also provide details of your disk
> > hardware (e.g. dmesg) and kernel configuration?
> 
> FreeBSD 6.0
> 
> Kernel is stock except for addition of:
> 
> 	device                atapicam        # needed to burn dvd
> 
> /boot/loader.conf:
> 
> 	console="comconsole"
> 	hw.ata.wc=0
        ^^^^^^^^^^^
"Make my hard drive go reeeeally slow please (just in case I crash)" :)

Kris
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