Re: Choosing a scheduler a boot time

[Tom Sightler <ttsig tuxyturvy com>]

On Mon, 2005-03-21 at 22:06 +0000, Stephen Gardner wrote:
> On Mon, 21 Mar 2005, Costa, Jeff wrote:
> 
> > I cannot seem to select a different scheduler in RHAS4 from the default
> > "cfq" scheduler. The scheduler choice appears to include any of these four
> > schedulers: completely fair queuing, deadline, anticipatory, and no-optimal.
> >
> > sched=cfg
> > sched=dead
> > sched=as
> > sched=noop
> 
> Jeff,
>  	Try elevator=  instead of sched=
> 
> Regards,
>  	Stephen

Not that this is your exact question, and the above should get your boot
time scheduler selection working, but you can also change the scheduler
via sysfs for a given block device at any time, even after boot.
Something like

echo "deadline" > /sys/block/hda/queue/scheduler

to select the deadline scheduler for only hda.  It's an excellent option
for benchmarking, or for systems that have different volumes with
distinctly different IO characteristics.

Later,
Tom