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    SubjectRe: [PATCH] Give kjournald a IOPRIO_CLASS_RT io priority
    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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