Kris Kennaway wrote:
>
> PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP is just in <pthread.h>.
>
> /*
> * Static initialization values.
> */
> #define PTHREAD_MUTEX_INITIALIZER NULL
> #define PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP NULL
> #define PTHREAD_COND_INITIALIZER NULL
> #define PTHREAD_RWLOCK_INITIALIZER NULL
>
>>>> I remembered mysql uses this macro to initialize spin mutex, and you
>>>> indead needs a patch to let it work
>>>
>>>
>>> No, with the code I committed mysql detects and uses it out of the
>>> box, without requiring any patches. It is easy to measure the
>>> resulting 30% performance improvement at high loads ;-)
>>>
>> see above, I didn't see any code set PTHREAD_MUTEX_ADAPTIVE_NP type.
>
> The code is already in mysql for use with glibc. It basically does
>
> #ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
> /*
> * Use PTHREAD_MUTEX_ADAPTIVE_NP for the mutexes we know will benefit
> * from it
> */
> ...
> #endif
>
> so it just works.
>
I can not find code in libthr setting mutex's member field m_type to
PTHREAD_MUTEX_ADAPTIVE_NP by your change, so how can it work as
expected ?