Re: [patch] cfq: ioprio inherit rt class

[Con Kolivas <kernel@kolivas.org>]

On Saturday 03 June 2006 03:12, Jens Axboe wrote:
> On Sat, May 27 2006, Con Kolivas wrote:
> > Jens, ml
> >
> > I was wondering if cfq io priorities should be explicitly set to the
> > realtime class when no io priority is specified from realtime tasks as in
> > the following patch? (rt_task() will need to be modified to suit the PI
> > changes in -mm)
>
> Not sure. RT io needs to be considered carefully, but I guess so does RT
> CPU scheduling. For now I'd prefer to play it a little safer, and only
> inheric the priority value and not the class.

The problem I envisioned with that was that realtime tasks, if they don't 
specify an io priority (as most current code doesn't), would basically get io 
priority 4 and have the same proportion as any nice 0 SCHED_NORMAL task 
whereas -nice tasks automatically are getting better io priority. How about 
givent them normal class but best priority so they are at least getting the 
same as nice -20?

-- 
-ck