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
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