Messages in this thread | | | Subject | Re: [PATCH 5/8] locking, mutex: Cancelable MCS lock for adaptive spinning | From | Jason Low <> | Date | Mon, 10 Feb 2014 13:15:59 -0800 |
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On Mon, 2014-02-10 at 20:58 +0100, Peter Zijlstra wrote: > +void osq_unlock(struct optimistic_spin_queue **lock) > +{ > + struct optimistic_spin_queue *node = this_cpu_ptr(&osq_node); > + struct optimistic_spin_queue *next; > + > + /* > + * Fast path for the uncontended case. > + */ > + if (likely(cmpxchg(lock, node, NULL) == node)) > + return;
Can we can also add the following code here as I'm noticing next != NULL is the much more likely scenario on my box:
next = xchg(&node->next, NULL); if (next) { ACCESS_ONCE(next->locked) = 1; return;
> + next = osq_wait_next(lock, node, NULL); > + if (next) > + ACCESS_ONCE(next->locked) = 1; > +}
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