Author: mjg
Date: Fri Nov 17 02:21:24 2017
New Revision: 325918
URL: https://svnweb.freebsd.org/changeset/base/325918
Log:
rwlock: avoid branches in the slow path if lockstat is disabled
Modified:
head/sys/kern/kern_rwlock.c
Modified: head/sys/kern/kern_rwlock.c
==============================================================================
--- head/sys/kern/kern_rwlock.c Fri Nov 17 02:21:07 2017 (r325917)
+++ head/sys/kern/kern_rwlock.c Fri Nov 17 02:21:24 2017 (r325918)
@@ -424,11 +424,14 @@ __rw_rlock_hard(volatile uintptr_t *c, struct thread *
struct lock_delay_arg lda;
#endif
#ifdef KDTRACE_HOOKS
- uintptr_t state;
u_int sleep_cnt = 0;
int64_t sleep_time = 0;
int64_t all_time = 0;
#endif
+#if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
+ uintptr_t state;
+ int doing_lockprof;
+#endif
if (SCHEDULER_STOPPED())
return;
@@ -440,12 +443,17 @@ __rw_rlock_hard(volatile uintptr_t *c, struct thread *
#endif
rw = rwlock2rw(c);
-#ifdef KDTRACE_HOOKS
- all_time -= lockstat_nsecs(&rw->lock_object);
-#endif
-#ifdef KDTRACE_HOOKS
+#ifdef LOCK_PROFILING
+ doing_lockprof = 1;
state = v;
+#elif defined(KDTRACE_HOOKS)
+ doing_lockprof = lockstat_enabled;
+ if (__predict_false(doing_lockprof)) {
+ all_time -= lockstat_nsecs(&rw->lock_object);
+ state = v;
+ }
#endif
+
for (;;) {
if (__rw_rlock_try(rw, td, &v, file, line))
break;
@@ -583,6 +591,10 @@ __rw_rlock_hard(volatile uintptr_t *c, struct thread *
__func__, rw);
v = RW_READ_VALUE(rw);
}
+#if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
+ if (__predict_true(!doing_lockprof))
+ return;
+#endif
#ifdef KDTRACE_HOOKS
all_time += lockstat_nsecs(&rw->lock_object);
if (sleep_time)
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