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    SubjectRe: [PATCH updated v2] sched/fair: core wide cfs task priority comparison
    On Fri, May 08, 2020 at 04:44:19PM +0800, Aaron Lu wrote:
    > On Wed, May 06, 2020 at 04:35:06PM +0200, Peter Zijlstra wrote:

    > > Aside from this being way to complicated for what it does -- you
    > > could've saved the min_vruntime for each rq and compared them with
    > > subtraction -- it is also terminally broken afaict.
    > >
    > > Consider any infeasible weight scenario. Take for instance two tasks,
    > > each bound to their respective sibling, one with weight 1 and one with
    > > weight 2. Then the lower weight task will run ahead of the higher weight
    > > task without bound.
    >
    > I don't follow how this could happen. Even the lower weight task runs
    > first, after some time, the higher weight task will get its turn and
    > from then on, the higher weight task will get more chance to run(due to
    > its higher weight and thus, slower accumulation of vruntime).

    That seems to assume they're mutually exclusive. In that case, as I
    argued, we only have a single runqueue and then yes it works. But if
    they're not exclusive, and can run concurrently, it comes apart.

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