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SubjectRe: [PATCH] Give kjournald a IOPRIO_CLASS_RT io priority
On Thu, 2 Oct 2008 15:27:47 +0200
Jens Axboe <jens.axboe@oracle.com> wrote:

> On Thu, Oct 02 2008, Arjan van de Ven wrote:
> > On Thu, 2 Oct 2008 11:45:37 +0200
> > Jens Axboe <jens.axboe@oracle.com> wrote:
> >
> > >
> > > That's a good idea, just bump the priority a little bit. Arjan,
> > > did you test that out? I'd suggest just trying prio level 0 and
> > > still using best-effort scheduling. Probably still need the sync
> > > marking, would be interesting to experiment with though.
> >
> > I looked at 0 but it appears the 0 is the default for everyone...
> > if everyone just defaulted to > 0 then yes I would have picked 0.
>
> That's not correct, class BE and value 4 is the default (and the code
> defaults to that, if you haven't set a value yourself):
>
> #define IOPRIO_NORM (4)
> static inline int task_ioprio(struct io_context *ioc)
> {
> if (ioprio_valid(ioc->ioprio))
> return IOPRIO_PRIO_DATA(ioc->ioprio);
>
> return IOPRIO_NORM;
> }
>
> static inline int task_ioprio_class(struct io_context *ioc)
> {
> if (ioprio_valid(ioc->ioprio))
> return IOPRIO_PRIO_CLASS(ioc->ioprio);
>
> return IOPRIO_CLASS_BE;
> }
>
> So if you use IOPRIO_CLASS_BE and 0 for the ioprio, you will have the
> highest priority of the default scheduling class.

ok

I checked not by looking at the code, but running ionice -p <pid> on a
bunch of things and they came back as 0

>


--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org


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