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    SubjectRe: [PATCH] rtmutex: multiple candidate owners without unrelated boosting
    On 12/15/2010 01:00 AM, Steven Rostedt wrote:
    > On Wed, 2010-12-15 at 00:44 +0800, Lai Jiangshan wrote:
    >> On Tue, Dec 14, 2010 at 10:01 PM, Steven Rostedt <> wrote:
    >>>> This is the motivation of this patch.
    >>>> An approach(wrong): when C's priority become higher and B, we deprive
    >>>> the pending ownership from B and give it to C and wakeup C.
    >>>> But this approach may lead to livelock.
    >>> I'm curious to how this can cause a livelock. I'm not doubting you, but
    >>> I just woke up, and I'm only half way through my first cup of coffee.
    >> if B is deprived, B has go to sleep again. In rare condition,
    >> B,C 's priority are changed frequent, the pending ownership is
    >> given to B/ deprived from B and given to C/ deprived from C and given to B
    >> ......
    >> No task can go forward, it is a kind of livelock.
    > Hmm, to have C and B change prios frequently, they will need to either
    > have someone in some for loop doing chrt on them (which is just bad), or
    > have lots of RT tasks constantly blocking on tasks that they own, which
    > is also bad. I find this far from a livelock, and any case that does
    > this would have more issues than causing a livelock here.

    Hi, Thomas,

    Do you think this is a kind of livelock.
    If it is not, I will send a much simpler patch.


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