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SubjectRe: [PATCH v9 05/19] qspinlock: Optimize for smaller NR_CPUS
On 04/18/2014 03:46 AM, Ingo Molnar wrote:
> * Waiman Long<waiman.long@hp.com> wrote:
>
>> On 04/17/2014 11:58 AM, Peter Zijlstra wrote:
>>> On Thu, Apr 17, 2014 at 11:03:57AM -0400, Waiman Long wrote:
>>>> +static __always_inline void
>>>> +clear_pending_set_locked(struct qspinlock *lock, u32 val)
>>>> +{
>>>> + struct __qspinlock *l = (void *)lock;
>>>> +
>>>> + ACCESS_ONCE(l->locked_pending) = 1;
>>>> +}
>>>> @@ -157,8 +251,13 @@ static inline int trylock_pending(struct qspinlock *lock, u32 *pval)
>>>> * we're pending, wait for the owner to go away.
>>>> *
>>>> * *,1,1 -> *,1,0
>>>> + *
>>>> + * this wait loop must be a load-acquire such that we match the
>>>> + * store-release that clears the locked bit and create lock
>>>> + * sequentiality; this because not all try_clear_pending_set_locked()
>>>> + * implementations imply full barriers.
>>> You renamed the function referred in the above comment.
>>>
>> Sorry, will fix the comments.
> I suggest not renaming the function instead.
> try_clear_pending_set_locked() tells the intent in a clearer fashion.
>
> Thanks,
>
> Ingo

I usually use the word "try" if there is a possibility of failure.
However, the function will always succeed, albeit by waiting a bit in
some cases. That is why I remove "try" from the name.

-Longman


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