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Date: Tue, 30 Oct 2007 21:16:48 +0800
From: David Xu <davidxu@FreeBSD.org>
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To: Kris Kennaway <kris@FreeBSD.org>
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Cc: Daniel Eischen <deischen@FreeBSD.org>, cvs-src@FreeBSD.org,
	src-committers@FreeBSD.org, David Xu <davidxu@FreeBSD.org>,
	cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/lib/libthr/thread thr_mutex.c
 src/lib/libkse/thread thr_mutex.c src/include pthread.h
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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 ?