diff options
| author | Mateusz Guzik <mjg@FreeBSD.org> | 2017-11-25 20:08:11 +0000 |
|---|---|---|
| committer | Mateusz Guzik <mjg@FreeBSD.org> | 2017-11-25 20:08:11 +0000 |
| commit | 2e106e0427f1a2b32c90a2bfdf7ebbb880f65d70 (patch) | |
| tree | 04215befe372265d2ecceee0892b181434274a16 | |
| parent | d915a14ef094c8dfc1a5aee70e135abfec01d0f1 (diff) | |
| download | src-2e106e0427f1a2b32c90a2bfdf7ebbb880f65d70.tar.gz src-2e106e0427f1a2b32c90a2bfdf7ebbb880f65d70.zip | |
rwlock: stop re-reading the owner when going to sleep
Notes
Notes:
svn path=/head/; revision=326194
| -rw-r--r-- | sys/kern/kern_rwlock.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/sys/kern/kern_rwlock.c b/sys/kern/kern_rwlock.c index b54d1c2bf94d..c0bc0c7510b2 100644 --- a/sys/kern/kern_rwlock.c +++ b/sys/kern/kern_rwlock.c @@ -411,8 +411,8 @@ __rw_rlock_hard(struct rwlock *rw, struct thread *td, uintptr_t v LOCK_FILE_LINE_ARG_DEF) { struct turnstile *ts; + struct thread *owner; #ifdef ADAPTIVE_RWLOCKS - volatile struct thread *owner; int spintries = 0; int i, n; #endif @@ -531,6 +531,8 @@ __rw_rlock_hard(struct rwlock *rw, struct thread *td, uintptr_t v continue; } + owner = lv_rw_wowner(v); + #ifdef ADAPTIVE_RWLOCKS /* * The current lock owner might have started executing @@ -539,8 +541,7 @@ __rw_rlock_hard(struct rwlock *rw, struct thread *td, uintptr_t v * chain lock. If so, drop the turnstile lock and try * again. */ - if ((v & RW_LOCK_READ) == 0) { - owner = (struct thread *)RW_OWNER(v); + if (owner != NULL) { if (TD_IS_RUNNING(owner)) { turnstile_cancel(ts); continue; @@ -581,7 +582,8 @@ __rw_rlock_hard(struct rwlock *rw, struct thread *td, uintptr_t v #ifdef KDTRACE_HOOKS sleep_time -= lockstat_nsecs(&rw->lock_object); #endif - turnstile_wait(ts, rw_owner(rw), TS_SHARED_QUEUE); + MPASS(owner == rw_owner(rw)); + turnstile_wait(ts, owner, TS_SHARED_QUEUE); #ifdef KDTRACE_HOOKS sleep_time += lockstat_nsecs(&rw->lock_object); sleep_cnt++; @@ -850,8 +852,8 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF) uintptr_t tid; struct rwlock *rw; struct turnstile *ts; + struct thread *owner; #ifdef ADAPTIVE_RWLOCKS - volatile struct thread *owner; int spintries = 0; int i, n; #endif @@ -981,6 +983,7 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF) #endif ts = turnstile_trywait(&rw->lock_object); v = RW_READ_VALUE(rw); + owner = lv_rw_wowner(v); #ifdef ADAPTIVE_RWLOCKS /* @@ -990,8 +993,7 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF) * chain lock. If so, drop the turnstile lock and try * again. */ - if (!(v & RW_LOCK_READ)) { - owner = (struct thread *)RW_OWNER(v); + if (owner != NULL) { if (TD_IS_RUNNING(owner)) { turnstile_cancel(ts); continue; @@ -1045,7 +1047,8 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF) #ifdef KDTRACE_HOOKS sleep_time -= lockstat_nsecs(&rw->lock_object); #endif - turnstile_wait(ts, rw_owner(rw), TS_EXCLUSIVE_QUEUE); + MPASS(owner == rw_owner(rw)); + turnstile_wait(ts, owner, TS_EXCLUSIVE_QUEUE); #ifdef KDTRACE_HOOKS sleep_time += lockstat_nsecs(&rw->lock_object); sleep_cnt++; |