Author: mjg
Date: Sat Jan 13 00:05:31 2018
New Revision: 327905
URL: https://svnweb.freebsd.org/changeset/base/327905
Log:
rwlock: try regular read unlock even in the hard path
Saves on turnstile trips if the lock got more readers.
Modified:
head/sys/kern/kern_rwlock.c
Modified: head/sys/kern/kern_rwlock.c
==============================================================================
--- head/sys/kern/kern_rwlock.c Sat Jan 13 00:04:11 2018 (r327904)
+++ head/sys/kern/kern_rwlock.c Sat Jan 13 00:05:31 2018 (r327905)
@@ -771,9 +771,9 @@ __rw_runlock_hard(struct rwlock *rw, struct thread *td
turnstile_chain_lock(&rw->lock_object);
v = RW_READ_VALUE(rw);
retry_ts:
- if (__predict_false(RW_READERS(v) > 1)) {
+ if (__rw_runlock_try(rw, td, &v)) {
turnstile_chain_unlock(&rw->lock_object);
- continue;
+ break;
}
v &= (RW_LOCK_WAITERS | RW_LOCK_WRITE_SPINNER);
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