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Index: sys/conf/NOTES
===================================================================
--- sys/conf/NOTES
+++ sys/conf/NOTES
@@ -2841,3 +2841,6 @@
# Kernel support for stats(3).
options STATS
+
+# Dtrace-based profiling of __predict_true/false
+# options PREDICT_PROFILING
Index: sys/conf/options
===================================================================
--- sys/conf/options
+++ sys/conf/options
@@ -1012,3 +1012,6 @@
# gcov support
GCOV opt_global.h
LINDEBUGFS
+
+# Dtrace-based profiling of __predict_true/false
+PREDICT_PROFILING opt_global.h
Index: sys/kern/kern_sdt.c
===================================================================
--- sys/kern/kern_sdt.c
+++ sys/kern/kern_sdt.c
@@ -33,6 +33,9 @@
#include <sys/sdt.h>
SDT_PROVIDER_DEFINE(sdt);
+#ifdef PREDICT_PROFILING
+SDT_PROBE_DEFINE4(sdt, profile, predict, , "int", "int", "char *", "int");
+#endif
/*
* Hook for the DTrace probe function. The SDT provider will set this to
@@ -54,3 +57,13 @@
printf("sdt_probe_stub: unexpectedly called\n");
kdb_backtrace();
}
+
+#ifdef PREDICT_PROFILING
+int
+sdt_predict_profile(int exp_res, int predict, const char *file, int line)
+{
+
+ SDT_PROBE4(sdt, profile, predict, , exp_res, predict, file, line);
+ return (exp_res);
+}
+#endif
Index: sys/sys/cdefs.h
===================================================================
--- sys/sys/cdefs.h
+++ sys/sys/cdefs.h
@@ -447,11 +447,19 @@
* larger code.
*/
#if __GNUC_PREREQ__(2, 96)
-#define __predict_true(exp) __builtin_expect((exp), 1)
-#define __predict_false(exp) __builtin_expect((exp), 0)
+#define __predict_true_noprobe(exp) __builtin_expect((exp), 1)
+#define __predict_false_noprobe(exp) __builtin_expect((exp), 0)
#else
-#define __predict_true(exp) (exp)
-#define __predict_false(exp) (exp)
+#define __predict_true_noprobe(exp) (exp)
+#define __predict_false_noprobe(exp) (exp)
+#endif
+
+#ifdef PREDICT_PROFILING
+#define __predict_true(exp) sdt_predict_profile(exp, true, __FILE__, __LINE__)
+#define __predict_false(exp) sdt_predict_profile(exp, false, __FILE__, __LINE__)
+#else
+#define __predict_true(exp) __predict_true_noprobe(exp)
+#define __predict_false(exp) __predict_false_noprobe(exp)
#endif
#if __GNUC_PREREQ__(4, 0)
Index: sys/sys/lockstat.h
===================================================================
--- sys/sys/lockstat.h
+++ sys/sys/lockstat.h
@@ -116,7 +116,7 @@
LOCKSTAT_RECORD1(probe, lp, a); \
} while (0)
-#define LOCKSTAT_PROFILE_ENABLED(probe) __predict_false(lockstat_enabled)
+#define LOCKSTAT_PROFILE_ENABLED(probe) __predict_false_noprobe(lockstat_enabled)
struct lock_object;
uint64_t lockstat_nsecs(struct lock_object *);
Index: sys/sys/mutex.h
===================================================================
--- sys/sys/mutex.h
+++ sys/sys/mutex.h
@@ -240,7 +240,7 @@
uintptr_t _tid = (uintptr_t)(tid); \
uintptr_t _v = MTX_UNOWNED; \
\
- if (__predict_false(LOCKSTAT_PROFILE_ENABLED(adaptive__acquire) ||\
+ if (__predict_false_noprobe(LOCKSTAT_PROFILE_ENABLED(adaptive__acquire) ||\
!_mtx_obtain_lock_fetch((mp), &_v, _tid))) \
_mtx_lock_sleep((mp), _v, (opts), (file), (line)); \
} while (0)
@@ -257,7 +257,7 @@
uintptr_t _v = MTX_UNOWNED; \
\
spinlock_enter(); \
- if (__predict_false(LOCKSTAT_PROFILE_ENABLED(spin__acquire) || \
+ if (__predict_false_noprobe(LOCKSTAT_PROFILE_ENABLED(spin__acquire) || \
!_mtx_obtain_lock_fetch((mp), &_v, _tid))) \
_mtx_lock_spin((mp), _v, (opts), (file), (line)); \
} while (0)
@@ -308,7 +308,7 @@
#define __mtx_unlock(mp, tid, opts, file, line) do { \
uintptr_t _v = (uintptr_t)(tid); \
\
- if (__predict_false(LOCKSTAT_PROFILE_ENABLED(adaptive__release) ||\
+ if (__predict_false_noprobe(LOCKSTAT_PROFILE_ENABLED(adaptive__release) ||\
!_mtx_release_lock_fetch((mp), &_v))) \
_mtx_unlock_sleep((mp), _v, (opts), (file), (line)); \
} while (0)
Index: sys/sys/param.h
===================================================================
--- sys/sys/param.h
+++ sys/sys/param.h
@@ -40,6 +40,10 @@
#ifndef _SYS_PARAM_H_
#define _SYS_PARAM_H_
+#ifdef PREDICT_PROFILING
+int sdt_predict_profile(int, int, const char *, int);
+#endif
+
#include <sys/_null.h>
#define BSD 199506 /* System version (year & month). */
Index: sys/sys/rwlock.h
===================================================================
--- sys/sys/rwlock.h
+++ sys/sys/rwlock.h
@@ -107,7 +107,7 @@
uintptr_t _tid = (uintptr_t)(tid); \
uintptr_t _v = RW_UNLOCKED; \
\
- if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__acquire) || \
+ if (__predict_false_noprobe(LOCKSTAT_PROFILE_ENABLED(rw__acquire) || \
!_rw_write_lock_fetch((rw), &_v, _tid))) \
_rw_wlock_hard((rw), _v, (file), (line)); \
} while (0)
@@ -116,7 +116,7 @@
#define __rw_wunlock(rw, tid, file, line) do { \
uintptr_t _v = (uintptr_t)(tid); \
\
- if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__release) || \
+ if (__predict_false_noprobe(LOCKSTAT_PROFILE_ENABLED(rw__release) || \
!_rw_write_unlock_fetch((rw), &_v))) \
_rw_wunlock_hard((rw), _v, (file), (line)); \
} while (0)
Index: sys/sys/sdt.h
===================================================================
--- sys/sys/sdt.h
+++ sys/sys/sdt.h
@@ -165,11 +165,11 @@
#define SDT_PROBE_DECLARE(prov, mod, func, name) \
extern struct sdt_probe sdt_##prov##_##mod##_##func##_##name[1]
-#define SDT_PROBES_ENABLED() __predict_false(sdt_probes_enabled)
+#define SDT_PROBES_ENABLED() __predict_false_noprobe(sdt_probes_enabled)
#define SDT_PROBE(prov, mod, func, name, arg0, arg1, arg2, arg3, arg4) do { \
if (SDT_PROBES_ENABLED()) { \
- if (__predict_false(sdt_##prov##_##mod##_##func##_##name->id)) \
+ if (__predict_false_noprobe(sdt_##prov##_##mod##_##func##_##name->id)) \
(*sdt_probe_func)(sdt_##prov##_##mod##_##func##_##name->id, \
(uintptr_t) arg0, (uintptr_t) arg1, (uintptr_t) arg2, \
(uintptr_t) arg3, (uintptr_t) arg4); \
@@ -427,6 +427,8 @@
void sdt_probe_stub(uint32_t, uintptr_t, uintptr_t, uintptr_t, uintptr_t,
uintptr_t);
+int sdt_predict_trace(int exp_res, int predict, const char *file, int line);
+
SDT_PROVIDER_DECLARE(sdt);
#endif /* _KERNEL */
Index: sys/sys/sx.h
===================================================================
--- sys/sys/sx.h
+++ sys/sys/sx.h
@@ -163,7 +163,7 @@
uintptr_t v = SX_LOCK_UNLOCKED;
int error = 0;
- if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__acquire) ||
+ if (__predict_false_noprobe(LOCKSTAT_PROFILE_ENABLED(sx__acquire) ||
!atomic_fcmpset_acq_ptr(&sx->sx_lock, &v, tid)))
error = _sx_xlock_hard(sx, v, opts);
@@ -176,7 +176,7 @@
{
uintptr_t x = (uintptr_t)td;
- if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__release) ||
+ if (__predict_false_noprobe(LOCKSTAT_PROFILE_ENABLED(sx__release) ||
!atomic_fcmpset_rel_ptr(&sx->sx_lock, &x, SX_LOCK_UNLOCKED)))
_sx_xunlock_hard(sx, x);
}
Index: sys/sys/systm.h
===================================================================
--- sys/sys/systm.h
+++ sys/sys/systm.h
@@ -298,7 +298,7 @@
__compiler_membar();
td->td_critnest--;
__compiler_membar();
- if (__predict_false(td->td_owepreempt))
+ if (__predict_false_noprobe(td->td_owepreempt))
critical_exit_preempt();
}

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