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    SubjectRe: [RFC v5 2/9] sched/deadline: improve the tracking of active utilization
    On Fri, 24 Mar 2017 22:47:15 +0100
    luca abeni <luca.abeni@santannapisa.it> wrote:

    > Ok... Since I am not good at ascii art, would it be ok to add a textual
    > description? If yes, I'll add a comment like:
    > "
    > The utilization of a task is added to the runqueue's active utilization
    > when the task becomes active (is enqueued in the runqueue), and is
    > removed when the task becomes inactive. A task does not become
    > immediately inactive when it blocks, but becomes inactive at the so
    > called "0 lag time"; so, we setup the "inactive timer" to fire at the
    > "0 lag time". When the "inactive timer" fires, the task utilization is
    > removed from the runqueue's active utilization. If the task wakes up
    > again on the same runqueue before the "0 lag time", the active
    > utilization must not be changed and the "inactive timer" must be
    > cancelled. If the task wakes up again on a different runqueue before
    > the "0 lag time", then the task's utilization must be removed from the
    > previous runqueue's active utilization and must be added to the new
    > runqueue's active utilization.
    > In order to avoid races between a task waking up on a runqueue while the
    > "inactive timer" is running on a different CPU, the "dl_non_contending"
    > flag is used to indicate that a task is not on a runqueue but is active
    > (so, the flag is set when the task blocks and is cleared when the
    > "inactive timer" fires or when the task wakes up).

    Sure, the above is great if you never want anyone to read it ;)

    Can you please break it up a little. My head starts to spin by the
    third line down.

    -- Steve

    > "
    > (if this is ok, where can I add this comment?)

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