From 6af8e23e6b7760cd36660465ee32aaf2bd0d7306 Mon Sep 17 00:00:00 2001
From: Fabian Keil <fk@fabiankeil.de>
Date: Fri, 4 Sep 2015 20:07:22 +0200
Subject: [PATCH 088/325] share/dtrace: Import fbt-time

... which llquantizes the time spent in a given kernel function

Among other things this can be useful for general system
tuning and analysis of lock contention (once you know
where to expect it).

Obtained from: ElectroBSD
---
 share/dtrace/Makefile |  1 +
 share/dtrace/fbt-time | 80 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)
 create mode 100755 share/dtrace/fbt-time

diff --git a/share/dtrace/Makefile b/share/dtrace/Makefile
index 62b91e24d1f9..1297a3317dc8 100644
--- a/share/dtrace/Makefile
+++ b/share/dtrace/Makefile
@@ -8,6 +8,7 @@
 SCRIPTS=	blocking \
 		disklatency \
 		disklatencycmd \
+		fbt-time \
 		geli-key-monitor \
 		hotopen \
 		look-who-is-reaping \
diff --git a/share/dtrace/fbt-time b/share/dtrace/fbt-time
new file mode 100755
index 000000000000..27a950b63a0c
--- /dev/null
+++ b/share/dtrace/fbt-time
@@ -0,0 +1,80 @@
+#!/usr/sbin/dtrace -s
+
+/***************************************************************************
+ * fbt-time
+ *
+ * Measures the time spent in a given kernel function and llquantizes
+ * the results for the traced calls. Example output can be seen at:
+ * http://www.fabiankeil.de/gehacktes/electrobsd/zfs-arc-tuning/
+ *
+ * WARNING: Tracing kernel functions that get executed several thousand
+ *          times per second may negatively impact system performance
+ *          and can even cause brief lockups. Before using this script
+ *          on production systems you may want to sample the traced
+ *          kernel function first.
+ *
+ * XXX: This script should be fleshed out to be more resilient to
+ * incorrect input and provide more awesome stats. A better name
+ * would be nice, too.
+ *
+ * Copyright (c) 2014 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
+{
+    traced_function = $$1;
+
+    multiple = "microseconds";
+    divisor = 1000;
+    executions = 0;
+
+    this->timestamp = walltimestamp;
+    this->msecs = (this->timestamp / 1000000) % 1000;
+    printf("%Y.%.3d: Tracing '%s'. Hit CTRL-C to exit.\n",
+           this->timestamp, this->msecs, traced_function);
+}
+
+fbt::$$1:entry
+{
+        self->timestamp = timestamp;
+        executions++;
+}
+
+fbt::$$1:return
+/self->timestamp/
+{
+        this->elapsed = (timestamp - self->timestamp) / divisor;
+        @elapsed_time = llquantize(this->elapsed, 10, 0, 5, 10);
+        @elapsed_avg["Average"] = avg(this->elapsed);
+        self->elapsed = 0;
+}
+
+tick-10sec,
+END
+/executions/
+{
+        printf("%Y: Runtime for %s() in %s\n", walltimestamp, traced_function, multiple);
+        printa(@elapsed_avg);
+        printa(@elapsed_time);
+}
+
+END
+/executions == 0/
+{
+        printf("%Y: Looks like %s() wasn't called yet.\n", walltimestamp, traced_function);
+}
-- 
2.32.0