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    SubjectRe: [patch 05/15] Generic Mutex Subsystem, mutex-core.patch

    * Oleg Nesterov <oleg@tv-sign.ru> wrote:

    > > +__mutex_wakeup_waiter(struct mutex *lock __IP_DECL__)
    > > +{
    > > + struct mutex_waiter *waiter;
    > > ...
    > > + if (!waiter->woken) {
    > > + waiter->woken = 1;
    > > + wake_up_process(waiter->ti->task);
    > > + }
    >
    > Is it optimization? If yes - why? From mutex.h:
    >
    > - only one task can hold the mutex at a time
    > - only the owner can unlock the mutex
    >
    > So, how can this help?

    yes, it's an optimization. I've removed it from the latest queue because
    it didnt trigger all that often, but the optimization is valid: while we
    have a 'waiter in flight', another (fast) task might grab the mutex, and
    might release it - in which case it could attempt to wake up the waiter
    again - which this flag optimizes.

    Ingo
    -
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