general LOCK_PROFILING cleanup

- only collect timestamps when a lock is contested - this reduces the overhead
  of collecting profiles from 20x to 5x

- remove unused function from subr_lock.c

- generalize cnt_hold and cnt_lock statistics to be kept for all locks

- NOTE: rwlock profiling generates invalid statistics (and most likely always has)
  someone familiar with that should review

1 files changed, 6 insertions, 10 deletions

diff --git a/sys/kern/kern_sx.c b/sys/kern/kern_sx.c
index ecab0e91a599..e0bff421c2d7 100644
--- a/sys/kern/kern_sx.c
+++ b/sys/kern/kern_sx.c
@@ -111,7 +111,7 @@ void
 _sx_slock(struct sx *sx, const char *file, int line)
 {
 	uint64_t waittime = 0;
-	int contested;
+	int contested = 0;
 
 	mtx_lock(sx->sx_lock);
 	KASSERT(sx->sx_xholder != curthread,
@@ -122,11 +122,9 @@ _sx_slock(struct sx *sx, const char *file, int line)
 	/*
 	 * Loop in case we lose the race for lock acquisition.
 	 */
-        if (sx->sx_cnt < 0)
-		lock_profile_waitstart(&waittime);
 	while (sx->sx_cnt < 0) {
 		sx->sx_shrd_wcnt++;
-		lock_profile_obtain_lock_failed(&sx->sx_object, &contested);
+		lock_profile_obtain_lock_failed(&sx->sx_object, &contested, &waittime);
 		cv_wait(&sx->sx_shrd_cv, sx->sx_lock);
 		sx->sx_shrd_wcnt--;
 	}
@@ -135,7 +133,7 @@ _sx_slock(struct sx *sx, const char *file, int line)
 	sx->sx_cnt++;
 
         if (sx->sx_cnt == 1)
-		lock_profile_obtain_lock_success(&sx->sx_object, waittime, file, line);
+		lock_profile_obtain_lock_success(&sx->sx_object, contested, waittime, file, line);
 
 	LOCK_LOG_LOCK("SLOCK", &sx->sx_object, 0, 0, file, line);
 	WITNESS_LOCK(&sx->sx_object, 0, file, line);
@@ -166,7 +164,7 @@ _sx_try_slock(struct sx *sx, const char *file, int line)
 void
 _sx_xlock(struct sx *sx, const char *file, int line)
 {
-	int contested;
+	int contested = 0;
 	uint64_t waittime = 0;
 
 	mtx_lock(sx->sx_lock);
@@ -184,12 +182,10 @@ _sx_xlock(struct sx *sx, const char *file, int line)
 	WITNESS_CHECKORDER(&sx->sx_object, LOP_NEWORDER | LOP_EXCLUSIVE, file,
 	    line);
 
-        if (sx->sx_cnt)
-		lock_profile_waitstart(&waittime);
 	/* Loop in case we lose the race for lock acquisition. */
 	while (sx->sx_cnt != 0) {
 		sx->sx_excl_wcnt++;
-		lock_profile_obtain_lock_failed(&sx->sx_object, &contested);
+		lock_profile_obtain_lock_failed(&sx->sx_object, &contested, &waittime);
 		cv_wait(&sx->sx_excl_cv, sx->sx_lock);
 		sx->sx_excl_wcnt--;
 	}
@@ -200,7 +196,7 @@ _sx_xlock(struct sx *sx, const char *file, int line)
 	sx->sx_cnt--;
 	sx->sx_xholder = curthread;
 
-	lock_profile_obtain_lock_success(&sx->sx_object, waittime, file, line);
+	lock_profile_obtain_lock_success(&sx->sx_object, contested, waittime, file, line);
 	LOCK_LOG_LOCK("XLOCK", &sx->sx_object, 0, 0, file, line);
 	WITNESS_LOCK(&sx->sx_object, LOP_EXCLUSIVE, file, line);
 	curthread->td_locks++;