Get number of CPUs and ignore spin count on single processor machine.

3 files changed, 15 insertions, 6 deletions

diff --git a/lib/libthr/thread/thr_init.c b/lib/libthr/thread/thr_init.c
index 1150985..5d1aae5 100644
--- a/lib/libthr/thread/thr_init.c
+++ b/lib/libthr/thread/thr_init.c
@@ -99,6 +99,7 @@ struct pthread_cond_attr _pthread_condattr_default = {
 };
 
 pid_t		_thr_pid;
+int		_thr_smp_cpus = 1;
 size_t		_thr_guard_default;
 size_t		_thr_stack_default = THR_STACK_DEFAULT;
 size_t		_thr_stack_initial = THR_STACK_INITIAL;
@@ -443,6 +444,8 @@ init_private(void)
 		len = sizeof (_usrstack);
 		if (sysctl(mib, 2, &_usrstack, &len, NULL, 0) == -1)
 			PANIC("Cannot get kern.usrstack from sysctl");
+		len = sizeof(_thr_smp_cpus);
+		sysctlbyname("kern.smp.cpus", &_thr_smp_cpus, &len, NULL, 0);
 		_thr_page_size = getpagesize();
 		_thr_guard_default = _thr_page_size;
 		_pthread_attr_default.guardsize_attr = _thr_guard_default;
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index 29993ec..bb6c999 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -588,6 +588,8 @@ extern struct pthread_cond_attr _pthread_condattr_default __hidden;
 extern struct pthread_prio _thr_priorities[] __hidden;
 
 extern pid_t	_thr_pid __hidden;
+extern int	_thr_smp_cpus __hidden;
+
 extern size_t	_thr_guard_default __hidden;
 extern size_t	_thr_stack_default __hidden;
 extern size_t	_thr_stack_initial __hidden;
diff --git a/lib/libthr/thread/thr_pspinlock.c b/lib/libthr/thread/thr_pspinlock.c
index ec3d68b..561ac26 100644
--- a/lib/libthr/thread/thr_pspinlock.c
+++ b/lib/libthr/thread/thr_pspinlock.c
@@ -104,13 +104,17 @@ _pthread_spin_lock(pthread_spinlock_t *lock)
 		count = SPIN_COUNT;
 		while ((ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock)) != 0) {
 			while (lck->s_lock) {
-#ifdef __i386__
-				/* tell cpu we are spinning */
-				__asm __volatile("pause");
-#endif
-				if (--count <= 0) {
-					count = SPIN_COUNT;
+				if (_thr_smp_cpus <= 1) {
 					_pthread_yield();
+				} else {
+#if defined(__i386__) || defined(__x86_64__)
+					/* tell cpu we are spinning */
+					__asm __volatile("pause");
+#endif
+					if (--count <= 0) {
+						count = SPIN_COUNT;
+						_pthread_yield();
+					}
 				}
 			}
 		}