Messages in this thread | | | Date | Fri, 18 Apr 2014 12:26:26 -0400 | From | Waiman Long <> | Subject | Re: [PATCH v9 05/19] qspinlock: Optimize for smaller NR_CPUS |
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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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