Messages in this thread | | | Date | Thu, 2 Oct 2008 18:42:11 +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 15:47:37 +0200 > Jens Axboe <jens.axboe@oracle.com> wrote: > > > Yes, it'll report '0' which means 'not set'. The kernel inteprets 'not > > set' as the default values, BE/4. There's a big diffence, since '0' > > means that we track CPU nice values where as if it returned be/4 then > > that is a strict/fixed setting. > > argh. "0" means both "not set" and "highest priority".
Arjan, please read the interface, it does not...
0 means not set, period. What matters is the class setting, if that is non-zero then it is a valid setting. See
#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
So highest priority BE is IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, 0), which is of course valid.
-- Jens Axboe
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