geom_sched usage

[Luigi Rizzo]

On Tue, Oct 19, 2010 at 08:07:54AM +0200, David Naylor wrote:
> On Monday 18 October 2010 21:51:25 Luigi Rizzo wrote:
...
> > >  - is there anyway to automatically attach gsched to a device on startup
> > >  (i.e.
> > > 
> > > in rc.conf)?
> > 
> > no, you have to build some script yourself.
> 
> Would there be any interest in having a rc.d/ script?  I would find it 
> conveniant to specify a single rc.conf line and get scheduling for all my 
> devices.  PC-BSD might find such functionality useful.  
> 
> See attached for my first draft at such a script, I'm willing to hash it into 
> shape.  

it would surely be useful but try to keep it simple and user-driven
(this is a general comment on rc.d scripts).
Some things i think you should simplify in your script:
- remove support for guessing which devices should get the scheduler.
  This is really a user decision and if the user names no devices then
  i believe it is better/safer not to install any scheduler.
- use standard names such as gsched_flags or gsched_flags_${dev} to hold 
  generic and specific flags for the insert command.
  It is neither useful nor flexible to have the script insert '-a'
  in front of the algorithm;

cheers
luigi