On Fri, 20 May 2016, Peter Zijlstra wrote:
On Fri, May 20, 2016 at 08:00:49AM -0700, Davidlohr Bueso wrote:
On Fri, 20 May 2016, Peter Zijlstra wrote:
>On Thu, May 19, 2016 at 10:39:26PM -0700, Davidlohr Bueso wrote:
>> In addition, this makes me wonder if queued_spin_is_locked() should then be:
>>
>>- return atomic_read(&lock->val);
>>+ return atomic_read(&lock->val) & _Q_LOCKED_MASK;
>>
>>And avoid considering pending waiters as locked.
>
>Probably
Similarly, and I know you hate it, but afaict, then semantically
queued_spin_is_contended() ought to be:
- return atomic_read(&lock->val) & ~_Q_LOCKED_MASK;
+ return atomic_read(&lock->val);
Nah, that would make it return true for (0,0,1), ie. uncontended locked.
Right, and we want:
(*, 1, 1)
(*, 1, 0)
(n, 0, 0)
I may be missing some combinations, its still early.
