From cf940165d4caf132405a3fe3df58b57eb735ac04 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sun, 25 Sep 2011 21:10:50 -0400 Subject: [PATCH] optimize cond waiter move using atomic swap instead of cas loop --- src/thread/pthread_cond_broadcast.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/src/thread/pthread_cond_broadcast.c b/src/thread/pthread_cond_broadcast.c index 7e5ea91c..4fab9994 100644 --- a/src/thread/pthread_cond_broadcast.c +++ b/src/thread/pthread_cond_broadcast.c @@ -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. */ -- 2.25.1