spin before waiting on futex in mutex and rwlock lock operations

[musl] / src / thread / pthread_mutex_timedlock.c

diff --git a/src/thread/pthread_mutex_timedlock.c b/src/thread/pthread_mutex_timedlock.c
index 2a959d2..116a8b7 100644 (file)
--- a/src/thread/pthread_mutex_timedlock.c
+++ b/src/thread/pthread_mutex_timedlock.c
@@ -8,6 +8,12 @@ int pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec *
 
        int r, t, priv = (m->_m_type & 128) ^ 128;
 
+       r = pthread_mutex_trylock(m);
+       if (r != EBUSY) return r;
+       
+       int spins = 100;
+       while (spins-- && m->_m_lock) a_spin();
+
        while ((r=pthread_mutex_trylock(m)) == EBUSY) {
                if (!(r=m->_m_lock) || ((r&0x40000000) && (m->_m_type&4)))
                        continue;