spin before waiting on futex in mutex and rwlock lock operations

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;

src/thread/pthread_rwlock_timedrdlock.c

@@ -3,6 +3,13 @@
 int pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rw, const struct timespec *restrict at)
 {
 	int r, t;
+
+	r = pthread_rwlock_tryrdlock(rw);
+	if (r != EBUSY) return r;
+	
+	int spins = 100;
+	while (spins-- && rw->_rw_lock) a_spin();
+
 	while ((r=pthread_rwlock_tryrdlock(rw))==EBUSY) {
 		if (!(r=rw->_rw_lock) || (r&0x7fffffff)!=0x7fffffff) continue;
 		t = r | 0x80000000;

src/thread/pthread_rwlock_timedwrlock.c

@@ -3,6 +3,13 @@
 int pthread_rwlock_timedwrlock(pthread_rwlock_t *restrict rw, const struct timespec *restrict at)
 {
 	int r, t;
+	
+	r = pthread_rwlock_trywrlock(rw);
+	if (r != EBUSY) return r;
+	
+	int spins = 100;
+	while (spins-- && rw->_rw_lock) a_spin();
+
 	while ((r=pthread_rwlock_trywrlock(rw))==EBUSY) {
 		if (!(r=rw->_rw_lock)) continue;
 		t = r | 0x80000000;