Messages in this thread |  | | | Date | Thu, 2 Oct 2008 15:27:47 +0200 | | From | Jens Axboe <> | | Subject | Re: [PATCH] Give kjournald a IOPRIO_CLASS_RT io priority |
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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.
-- Jens Axboe
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