cvs commit: src/lib/libthr/thread thr_cond.c thr_private.h thr_rwlock.c

[Kris Kennaway]

David Xu wrote:
> Jeff Roberson wrote:
>> On Mon, 31 Mar 2008, David Xu wrote:
>>
>>> davidxu     2008-03-31 02:55:50 UTC
>>>
>>>  FreeBSD src repository
>>>
>>>  Modified files:
>>>    lib/libthr/thread    thr_cond.c thr_private.h thr_rwlock.c
>>>  Log:
>>>  Rewrite rwlock to user atomic operations to change rwlock state, this
>>>  eliminates internal mutex lock contention when most rwlock operations
>>>  are read.
>>>
>>>  Orignal patch provided by: jeff
>>
>> Thanks David!
>>
>> Do you still plan to do kernel side support so we can totally 
>> eliminate the pthread mutex and condvars from rwlock?  I have evidence 
>> that this would produce further improvements.
>>
>> Jeff
> 
> I have pure kernel version working, sometimes locking kernel sleep
> chain is more expensive than a pure userland mutex locking, since
> kernel sleep chain lock is global. I am hestiate adding more code
> to kernel since I have tested mysql super-smack and sysbench
> read-only and seen no visible performance differences.
> all patches are here:
> 
> http://people.freebsd.org/~davidxu/patch/libthr_umtx_rwlock.diff

This patch appears to be incomplete (it also doesn't apply cleanly).

/zoo/kris/src8/lib/libthr/thread/thr_rwlock.c: In function 
'rwlock_rdlock_common':
/zoo/kris/src8/lib/libthr/thread/thr_rwlock.c:133: warning: implicit 
declaration of function '_thr_rwlock_tryrdlock'
/zoo/kris/src8/lib/libthr/thread/thr_rwlock.c:173: warning: implicit 
declaration of function '__thr_rwlock_rdlock'
/zoo/kris/src8/lib/libthr/thread/thr_rwlock.c: In function 
'_pthread_rwlock_trywrlock':
/zoo/kris/src8/lib/libthr/thread/thr_rwlock.c:246: warning: implicit 
declaration of function '_thr_rwlock_trywrlock'
/zoo/kris/src8/lib/libthr/thread/thr_rwlock.c: In function 
'_pthread_rwlock_unlock':
/zoo/kris/src8/lib/libthr/thread/thr_rwlock.c:275: warning: implicit 
declaration of function '_thr_rwlock_unlock'
/zoo/kris/src8/lib/libthr/thread/thr_rwlock.c: In function 
'rwlock_wrlock_common':
/zoo/kris/src8/lib/libthr/thread/thr_rwlock.c:331: warning: implicit 
declaration of function '__thr_rwlock_wrlock'
*** Error code 1

Kris