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optimize cond waiter move using atomic swap instead of cas loop

This commit is contained in:
Rich Felker 2011-09-25 21:10:50 -04:00
parent 09ec0f3aab
commit cf940165d4
1 changed files with 2 additions and 6 deletions
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8
src/thread/pthread_cond_broadcast.c
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@ -30,12 +30,8 @@ int pthread_cond_broadcast(pthread_cond_t *c)
}
/* Move waiter count to the mutex */
for (;;) {
w = c->_c_waiters;
a_fetch_add(&m->_m_waiters, w);
if (a_cas(&c->_c_waiters, w, 0) == w) break;
a_fetch_add(&m->_m_waiters, -w);
}
w = a_swap(&c->_c_waiters, 0);
a_fetch_add(&m->_m_waiters, w);
/* Perform the futex requeue, waking one waiter unless we know
* that the calling thread holds the mutex. */