From 73e490296c6838b4032e607f08a2569d85068952 Mon Sep 17 00:00:00 2001
From: Fabian Keil <fk@fabiankeil.de>
Date: Sat, 5 Sep 2015 22:46:09 +0200
Subject: [PATCH 087/325] usr/share/dtrace: Add look-who-is-reaping

It can be used to monitor and tune the ARC cache reaper.

The stack trace obviously isn't particular useful anymore
now that the reaper is called from a single location.

Obtained from: ElectroBSD
---
 share/dtrace/Makefile            |  1 +
 share/dtrace/look-who-is-reaping | 58 ++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)
 create mode 100755 share/dtrace/look-who-is-reaping

diff --git a/share/dtrace/Makefile b/share/dtrace/Makefile
index 6ae53bf6cbff..62b91e24d1f9 100644
--- a/share/dtrace/Makefile
+++ b/share/dtrace/Makefile
@@ -10,6 +10,7 @@ SCRIPTS=	blocking \
 		disklatencycmd \
 		geli-key-monitor \
 		hotopen \
+		look-who-is-reaping \
 		nfsattrstats \
 		nfsclienttime \
 		siftr \
diff --git a/share/dtrace/look-who-is-reaping b/share/dtrace/look-who-is-reaping
new file mode 100755
index 000000000000..0db6324a64f7
--- /dev/null
+++ b/share/dtrace/look-who-is-reaping
@@ -0,0 +1,58 @@
+#!/usr/sbin/dtrace -s
+
+/***************************************************************************
+ * look-who-is-reaping
+ *
+ * Collect stack traces for reap_arc_caches().
+ *
+ * Copyright (c) 2015 Fabian Keil <fk@fabiankeil.de>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ ***************************************************************************/
+
+#pragma D option quiet
+#pragma D option dynvarsize=10m
+
+dtrace:::BEGIN
+{
+    printf("%Y: Look who's (ARC cache) reaping .... Hit CTRL-C to exit.\n", walltimestamp);
+}
+
+fbt::reap_arc_caches:entry
+{
+        @reapers[probefunc,stack(3)] = count();
+        @reapers_total[probefunc,stack(3)] = count();
+        reaped++
+}
+
+tick-10s
+/reaped == 0/
+{
+         printf("%Y: The ARC cache reaper has not been seen for 10 seconds!\n", walltimestamp);
+}
+
+tick-10s
+/reaped/
+{
+        printf("%Y: The ARC reaper was called:\n", walltimestamp);
+        printa(@reapers);
+        trunc(@reapers);
+        reaped = 0
+}
+
+END
+/reaped/
+{
+        printf("%Y: The ARC reaper stats total:\n", walltimestamp);
+        printa(@reapers_total);
+}
-- 
2.32.0