rwlock: stop re-reading the owner when going to sleep
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parent
d915a14ef0
commit
2e106e0427
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=326194
@ -411,8 +411,8 @@ __rw_rlock_hard(struct rwlock *rw, struct thread *td, uintptr_t v
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LOCK_FILE_LINE_ARG_DEF)
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{
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struct turnstile *ts;
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struct thread *owner;
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#ifdef ADAPTIVE_RWLOCKS
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volatile struct thread *owner;
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int spintries = 0;
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int i, n;
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#endif
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@ -531,6 +531,8 @@ __rw_rlock_hard(struct rwlock *rw, struct thread *td, uintptr_t v
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continue;
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}
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owner = lv_rw_wowner(v);
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#ifdef ADAPTIVE_RWLOCKS
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/*
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* The current lock owner might have started executing
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@ -539,8 +541,7 @@ __rw_rlock_hard(struct rwlock *rw, struct thread *td, uintptr_t v
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* chain lock. If so, drop the turnstile lock and try
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* again.
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*/
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if ((v & RW_LOCK_READ) == 0) {
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owner = (struct thread *)RW_OWNER(v);
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if (owner != NULL) {
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if (TD_IS_RUNNING(owner)) {
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turnstile_cancel(ts);
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continue;
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@ -581,7 +582,8 @@ __rw_rlock_hard(struct rwlock *rw, struct thread *td, uintptr_t v
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#ifdef KDTRACE_HOOKS
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sleep_time -= lockstat_nsecs(&rw->lock_object);
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#endif
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turnstile_wait(ts, rw_owner(rw), TS_SHARED_QUEUE);
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MPASS(owner == rw_owner(rw));
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turnstile_wait(ts, owner, TS_SHARED_QUEUE);
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#ifdef KDTRACE_HOOKS
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sleep_time += lockstat_nsecs(&rw->lock_object);
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sleep_cnt++;
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@ -850,8 +852,8 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF)
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uintptr_t tid;
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struct rwlock *rw;
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struct turnstile *ts;
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struct thread *owner;
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#ifdef ADAPTIVE_RWLOCKS
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volatile struct thread *owner;
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int spintries = 0;
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int i, n;
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#endif
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@ -981,6 +983,7 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF)
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#endif
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ts = turnstile_trywait(&rw->lock_object);
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v = RW_READ_VALUE(rw);
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owner = lv_rw_wowner(v);
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#ifdef ADAPTIVE_RWLOCKS
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/*
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@ -990,8 +993,7 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF)
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* chain lock. If so, drop the turnstile lock and try
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* again.
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*/
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if (!(v & RW_LOCK_READ)) {
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owner = (struct thread *)RW_OWNER(v);
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if (owner != NULL) {
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if (TD_IS_RUNNING(owner)) {
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turnstile_cancel(ts);
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continue;
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@ -1045,7 +1047,8 @@ __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF)
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#ifdef KDTRACE_HOOKS
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sleep_time -= lockstat_nsecs(&rw->lock_object);
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#endif
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turnstile_wait(ts, rw_owner(rw), TS_EXCLUSIVE_QUEUE);
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MPASS(owner == rw_owner(rw));
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turnstile_wait(ts, owner, TS_EXCLUSIVE_QUEUE);
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#ifdef KDTRACE_HOOKS
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sleep_time += lockstat_nsecs(&rw->lock_object);
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sleep_cnt++;
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