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Tweak a few comments on adaptive spinning.

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This commit is contained in:
John Baldwin 2009-05-29 13:56:34 +00:00
parent f3ba9cc983
commit fa29f0236f
2 changed files with 15 additions and 6 deletions
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7
sys/kern/kern_mutex.c
View File

@ -399,8 +399,11 @@ _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file,
#ifdef ADAPTIVE_MUTEXES
/*
* If the current owner of the lock is executing on another
* CPU quit the hard path and try to spin.
* The current lock owner might have started executing
* on another CPU (or the lock could have changed
* owners) while we were waiting on the turnstile
* chain lock. If so, drop the turnstile lock and try
* again.
*/
owner = (struct thread *)(v & ~MTX_FLAGMASK);
if (TD_IS_RUNNING(owner)) {

14
sys/kern/kern_rwlock.c
View File

@ -412,8 +412,11 @@ _rw_rlock(struct rwlock *rw, const char *file, int line)
#ifdef ADAPTIVE_RWLOCKS
/*
* If the current owner of the lock is executing on another
* CPU quit the hard path and try to spin.
* The current lock owner might have started executing
* on another CPU (or the lock could have changed
* owners) while we were waiting on the turnstile
* chain lock. If so, drop the turnstile lock and try
* again.
*/
if ((v & RW_LOCK_READ) == 0) {
owner = (struct thread *)RW_OWNER(v);
@ -714,8 +717,11 @@ _rw_wlock_hard(struct rwlock *rw, uintptr_t tid, const char *file, int line)
#ifdef ADAPTIVE_RWLOCKS
/*
* If the current owner of the lock is executing on another
* CPU quit the hard path and try to spin.
* The current lock owner might have started executing
* on another CPU (or the lock could have changed
* owners) while we were waiting on the turnstile
* chain lock. If so, drop the turnstile lock and try
* again.
*/
if (!(v & RW_LOCK_READ)) {
owner = (struct thread *)RW_OWNER(v);