By default, don't compile in counters of calls to various time

query functions in the kernel, as these effectively serialize
parallel calls to the gettimeofday(2) system call, as well as
other kernel services that use timestamps.

Use the NetBSD version of the fix (kern_tc.c:1.32 by ad@) as
they have picked up our timecounter code and also ran into the
same problem.

Reported by:	kris
Obtained from:	NetBSD
MFC after:	3 days

1 files changed, 18 insertions, 13 deletions

diff --git a/sys/kern/kern_tc.c b/sys/kern/kern_tc.c
index c84054b..6409842 100644
--- a/sys/kern/kern_tc.c
+++ b/sys/kern/kern_tc.c
@@ -103,6 +103,7 @@ static int timestepwarnings;
 SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RW,
     &timestepwarnings, 0, "");
 
+#ifdef TC_COUNTERS
 #define TC_STATS(foo) \
 	static u_int foo; \
 	SYSCTL_UINT(_kern_timecounter, OID_AUTO, foo, CTLFLAG_RD, &foo, 0, "");\
@@ -114,7 +115,11 @@ TC_STATS(ngetbinuptime); TC_STATS(ngetnanouptime); TC_STATS(ngetmicrouptime);
 TC_STATS(ngetbintime);   TC_STATS(ngetnanotime);   TC_STATS(ngetmicrotime);
 TC_STATS(nsetclock);
 
+#define	TC_COUNT(var)	var++
 #undef TC_STATS
+#else
+#define	TC_COUNT(var)	/* nothing */
+#endif /* TC_COUNTERS */
 
 static void tc_windup(void);
 static void cpu_tick_calibrate(int);
@@ -180,7 +185,7 @@ binuptime(struct bintime *bt)
 	struct timehands *th;
 	u_int gen;
 
-	nbinuptime++;
+	TC_COUNT(nbinuptime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
@@ -194,7 +199,7 @@ nanouptime(struct timespec *tsp)
 {
 	struct bintime bt;
 
-	nnanouptime++;
+	TC_COUNT(nnanouptime);
 	binuptime(&bt);
 	bintime2timespec(&bt, tsp);
 }
@@ -204,7 +209,7 @@ microuptime(struct timeval *tvp)
 {
 	struct bintime bt;
 
-	nmicrouptime++;
+	TC_COUNT(nmicrouptime);
 	binuptime(&bt);
 	bintime2timeval(&bt, tvp);
 }
@@ -213,7 +218,7 @@ void
 bintime(struct bintime *bt)
 {
 
-	nbintime++;
+	TC_COUNT(nbintime);
 	binuptime(bt);
 	bintime_add(bt, &boottimebin);
 }
@@ -223,7 +228,7 @@ nanotime(struct timespec *tsp)
 {
 	struct bintime bt;
 
-	nnanotime++;
+	TC_COUNT(nnanotime);
 	bintime(&bt);
 	bintime2timespec(&bt, tsp);
 }
@@ -233,7 +238,7 @@ microtime(struct timeval *tvp)
 {
 	struct bintime bt;
 
-	nmicrotime++;
+	TC_COUNT(nmicrotime);
 	bintime(&bt);
 	bintime2timeval(&bt, tvp);
 }
@@ -244,7 +249,7 @@ getbinuptime(struct bintime *bt)
 	struct timehands *th;
 	u_int gen;
 
-	ngetbinuptime++;
+	TC_COUNT(ngetbinuptime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
@@ -258,7 +263,7 @@ getnanouptime(struct timespec *tsp)
 	struct timehands *th;
 	u_int gen;
 
-	ngetnanouptime++;
+	TC_COUNT(ngetnanouptime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
@@ -272,7 +277,7 @@ getmicrouptime(struct timeval *tvp)
 	struct timehands *th;
 	u_int gen;
 
-	ngetmicrouptime++;
+	TC_COUNT(ngetmicrouptime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
@@ -286,7 +291,7 @@ getbintime(struct bintime *bt)
 	struct timehands *th;
 	u_int gen;
 
-	ngetbintime++;
+	TC_COUNT(ngetbintime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
@@ -301,7 +306,7 @@ getnanotime(struct timespec *tsp)
 	struct timehands *th;
 	u_int gen;
 
-	ngetnanotime++;
+	TC_COUNT(ngetnanotime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
@@ -315,7 +320,7 @@ getmicrotime(struct timeval *tvp)
 	struct timehands *th;
 	u_int gen;
 
-	ngetmicrotime++;
+	TC_COUNT(ngetmicrotime);
 	do {
 		th = timehands;
 		gen = th->th_generation;
@@ -406,7 +411,7 @@ tc_setclock(struct timespec *ts)
 	struct bintime bt, bt2;
 
 	cpu_tick_calibrate(1);
-	nsetclock++;
+	TC_COUNT(nsetclock);
 	nanotime(&tbef);
 	timespec2bintime(ts, &bt);
 	binuptime(&bt2);