svn commit: r189545 - head/sys/kern

[Robert Watson]

Author: rwatson
Date: Sun Mar  8 22:19:28 2009
New Revision: 189545
URL: http://svn.freebsd.org/changeset/base/189545

Log:
  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

Modified:
  head/sys/kern/kern_tc.c

Modified: head/sys/kern/kern_tc.c
==============================================================================
--- head/sys/kern/kern_tc.c	Sun Mar  8 21:48:29 2009	(r189544)
+++ head/sys/kern/kern_tc.c	Sun Mar  8 22:19:28 2009	(r189545)
@@ -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(ngetna
 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);