diff --git a/include/sys/zfs_debug.h b/include/sys/zfs_debug.h
index 226aaa2b84..7e05c2a35f 100644
--- a/include/sys/zfs_debug.h
+++ b/include/sys/zfs_debug.h
@@ -41,6 +41,7 @@ extern "C" {
 extern int zfs_flags;
 extern int zfs_recover;
 extern int zfs_free_leak_on_eio;
+extern int zfs_dbgmsg_enable;
 
 #define	ZFS_DEBUG_DPRINTF		(1 << 0)
 #define	ZFS_DEBUG_DBUF_VERIFY		(1 << 1)
@@ -55,10 +56,22 @@ extern int zfs_free_leak_on_eio;
 
 extern void __dprintf(const char *file, const char *func,
     int line, const char *fmt, ...);
-#define	dprintf(...) \
-	__dprintf(__FILE__, __func__, __LINE__, __VA_ARGS__)
 #define	zfs_dbgmsg(...) \
-	__dprintf(__FILE__, __func__, __LINE__, __VA_ARGS__)
+	if (zfs_dbgmsg_enable) \
+		__dprintf(__FILE__, __func__, __LINE__, __VA_ARGS__)
+
+#ifdef ZFS_DEBUG
+/*
+ * To enable this:
+ *
+ * $ echo 1 >/sys/module/zfs/parameters/zfs_flags
+ */
+#define	dprintf(...) \
+	if (zfs_flags & ZFS_DEBUG_DPRINTF) \
+		__dprintf(__FILE__, __func__, __LINE__, __VA_ARGS__)
+#else
+#define	dprintf(...) ((void)0)
+#endif /* ZFS_DEBUG */
 
 extern void zfs_panic_recover(const char *fmt, ...);
 
diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index c6ff6171c1..9c0c5513d1 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -7138,6 +7138,7 @@ arc_tempreserve_space(uint64_t reserve, uint64_t txg)
 
 	if (reserve + arc_tempreserve + anon_size > arc_c / 2 &&
 	    anon_size > arc_c / 4) {
+#ifdef ZFS_DEBUG
 		uint64_t meta_esize =
 		    refcount_count(&arc_anon->arcs_esize[ARC_BUFC_METADATA]);
 		uint64_t data_esize =
@@ -7146,6 +7147,7 @@ arc_tempreserve_space(uint64_t reserve, uint64_t txg)
 		    "anon_data=%lluK tempreserve=%lluK arc_c=%lluK\n",
 		    arc_tempreserve >> 10, meta_esize >> 10,
 		    data_esize >> 10, reserve >> 10, arc_c >> 10);
+#endif
 		DMU_TX_STAT_BUMP(dmu_tx_dirty_throttle);
 		return (SET_ERROR(ERESTART));
 	}
diff --git a/module/zfs/dmu_send.c b/module/zfs/dmu_send.c
index d39ab1a9ea..36e412bdf3 100644
--- a/module/zfs/dmu_send.c
+++ b/module/zfs/dmu_send.c
@@ -3440,6 +3440,7 @@ receive_read_record(struct receive_arg *ra)
 static void
 dprintf_drr(struct receive_record_arg *rrd, int err)
 {
+#ifdef ZFS_DEBUG
 	switch (rrd->header.drr_type) {
 	case DRR_OBJECT:
 	{
@@ -3520,6 +3521,7 @@ dprintf_drr(struct receive_record_arg *rrd, int err)
 	default:
 		return;
 	}
+#endif
 }
 
 /*
diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index d71468db3c..5e2af24e3b 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -243,8 +243,7 @@ kmem_cache_t *spa_buffer_pool;
 int spa_mode_global;
 
 #ifdef ZFS_DEBUG
-/* Everything except dprintf and spa is on by default in debug builds */
-int zfs_flags = ~(ZFS_DEBUG_DPRINTF | ZFS_DEBUG_SPA);
+int zfs_flags = ~(ZFS_DEBUG_DPRINTF | ZFS_DEBUG_SET_ERROR | ZFS_DEBUG_SPA);
 #else
 int zfs_flags = 0;
 #endif
diff --git a/module/zfs/zfs_debug.c b/module/zfs/zfs_debug.c
index d1dba3f8f5..e2aff28e1f 100644
--- a/module/zfs/zfs_debug.c
+++ b/module/zfs/zfs_debug.c
@@ -33,20 +33,18 @@ int zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
 kstat_t *zfs_dbgmsg_kstat;
 
 /*
- * By default only enable the internal ZFS debug messages when running
- * in userspace (ztest).  The kernel log must be manually enabled.
+ * Internal ZFS debug messages are enabled by default.
  *
- * # Enable the kernel debug message log.
- * echo 1 > /sys/module/zfs/parameters/zfs_dbgmsg_enable
+ * # Print debug messages
+ * cat /proc/spl/kstat/zfs/dbgmsg
+ *
+ * # Disable the kernel debug message log.
+ * echo 0 > /sys/module/zfs/parameters/zfs_dbgmsg_enable
  *
  * # Clear the kernel debug message log.
  * echo 0 >/proc/spl/kstat/zfs/dbgmsg
  */
-#if defined(_KERNEL) && !defined(ZFS_DEBUG)
-int zfs_dbgmsg_enable = 0;
-#else
 int zfs_dbgmsg_enable = 1;
-#endif
 
 static int
 zfs_dbgmsg_headers(char *buf, size_t size)
@@ -164,6 +162,11 @@ __zfs_dbgmsg(char *buf)
 void
 __set_error(const char *file, const char *func, int line, int err)
 {
+	/*
+	 * To enable this:
+	 *
+	 * $ echo 512 >/sys/module/zfs/parameters/zfs_flags
+	 */
 	if (zfs_flags & ZFS_DEBUG_SET_ERROR)
 		__dprintf(file, func, line, "error %lu", err);
 }
@@ -179,10 +182,6 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
 	char *nl;
 	int i;
 
-	if (!zfs_dbgmsg_enable &&
-	    !(zfs_flags & (ZFS_DEBUG_DPRINTF | ZFS_DEBUG_SET_ERROR)))
-		return;
-
 	size = 1024;
 	buf = kmem_alloc(size, KM_SLEEP);
 
@@ -215,28 +214,23 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
 	 * To get this data enable the zfs__dprintf trace point as shown:
 	 *
 	 * # Enable zfs__dprintf tracepoint, clear the tracepoint ring buffer
-	 * $ echo 1 > /sys/module/zfs/parameters/zfs_flags
 	 * $ echo 1 > /sys/kernel/debug/tracing/events/zfs/enable
 	 * $ echo 0 > /sys/kernel/debug/tracing/trace
 	 *
 	 * # Dump the ring buffer.
 	 * $ cat /sys/kernel/debug/tracing/trace
 	 */
-	if (zfs_flags & (ZFS_DEBUG_DPRINTF | ZFS_DEBUG_SET_ERROR))
-		DTRACE_PROBE1(zfs__dprintf, char *, buf);
+	DTRACE_PROBE1(zfs__dprintf, char *, buf);
 
 	/*
-	 * To get this data enable the zfs debug log as shown:
+	 * To get this data:
 	 *
-	 * # Set zfs_dbgmsg enable, clear the log buffer
-	 * $ echo 1 > /sys/module/zfs/parameters/zfs_dbgmsg_enable
-	 * $ echo 0 > /proc/spl/kstat/zfs/dbgmsg
-	 *
-	 * # Dump the log buffer.
 	 * $ cat /proc/spl/kstat/zfs/dbgmsg
+	 *
+	 * To clear the buffer:
+	 * $ echo 0 > /proc/spl/kstat/zfs/dbgmsg
 	 */
-	if (zfs_dbgmsg_enable)
-		__zfs_dbgmsg(buf);
+	__zfs_dbgmsg(buf);
 
 	kmem_free(buf, size);
 }