At the request of several developers, restore the DIAGNOSIC code

deleted in 1.81. Increase the initial timeout limit to 2ms to
eliminate spurious messages of excessive timeouts in the NFS
client code.

Requested by:	Poul-Henning Kamp <phk@phk.freebsd.dk>
Requested by:	Mike Silbersack <silby@silby.com>
Requested by:	Sam Leffler <sam@errno.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/sys/kern/kern_timeout.c b/sys/kern/kern_timeout.c
index f1c4b90..8878500 100644
--- a/sys/kern/kern_timeout.c
+++ b/sys/kern/kern_timeout.c
@@ -70,6 +70,9 @@ int callwheelsize, callwheelbits, callwheelmask;
 struct callout_tailq *callwheel;
 int softticks;			/* Like ticks, but for softclock(). */
 struct mtx callout_lock;
+#ifdef DIAGNOSTIC
+struct mtx callout_dont_sleep;
+#endif
 
 static struct callout *nextsoftcheck;	/* Next callout to be checked. */
 
@@ -120,6 +123,9 @@ kern_timeout_callwheel_init(void)
 		TAILQ_INIT(&callwheel[i]);
 	}
 	mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
+#ifdef DIAGNOSTIC
+	mtx_init(&callout_dont_sleep, "callout_dont_sleep", NULL, MTX_DEF);
+#endif
 }
 
 /*
@@ -148,6 +154,11 @@ softclock(void *dummy)
 	int depth;
 	int mpcalls;
 	int gcalls;
+#ifdef DIAGNOSTIC
+	struct bintime bt1, bt2;
+	struct timespec ts2;
+	static uint64_t maxdt = 36893488147419102LL;	/* 2 msec */
+#endif
 
 #ifndef MAX_SOFTCLOCK_STEPS
 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
@@ -207,7 +218,24 @@ softclock(void *dummy)
 				} else {
 					mpcalls++;
 				}
+#ifdef DIAGNOSTIC
+				binuptime(&bt1);
+				mtx_lock(&callout_dont_sleep);
+#endif
 				c_func(c_arg);
+#ifdef DIAGNOSTIC
+				mtx_unlock(&callout_dont_sleep);
+				binuptime(&bt2);
+				bintime_sub(&bt2, &bt1);
+				if (bt2.frac > maxdt) {
+					maxdt = bt2.frac;
+					bintime2timespec(&bt2, &ts2);
+					printf(
+			"Expensive timeout(9) function: %p(%p) %ld.%09ld s\n",
+					c_func, c_arg,
+					(long)ts2.tv_sec, ts2.tv_nsec);
+				}
+#endif
 				if (!(c_flags & CALLOUT_MPSAFE))
 					mtx_unlock(&Giant);
 				mtx_lock_spin(&callout_lock);