- >500 static DTrace probes for the linuxulator

- DTrace scripts to check for errors, performance, ...
  they serve mostly as examples of what you can do with the static probe;s
  with moderate load the scripts may be overwhelmed, excessive lock-tracing
  may influence program behavior (see the last design decission)

Design decissions:
 - use "linuxulator" as the provider for the native bitsize; add the
   bitsize for the non-native emulation (e.g. "linuxuator32" on amd64)
 - Add probes only for locks which are acquired in one function and released
   in another function. Locks which are aquired and released in the same
   function should be easy to pair in the code, inter-function
   locking is more easy to verify in DTrace.
 - Probes for locks should be fired after locking and before releasing to
   prevent races (to provide data/function stability in DTrace, see the
   man-page of "dtrace -v ..." and the corresponding DTrace docs).

1 files changed, 94 insertions, 0 deletions

diff --git a/sys/compat/linux/stats_timing.d b/sys/compat/linux/stats_timing.d
new file mode 100644
index 000000000000..d0b6f73c654c
--- /dev/null
+++ b/sys/compat/linux/stats_timing.d
@@ -0,0 +1,94 @@
+#!/usr/sbin/dtrace -qs
+
+/*-
+ * Copyright (c) 2008-2012 Alexander Leidinger <netchild@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer
+ *    in this position and unchanged.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+/**
+ * Some statistics (all per provider):
+ *  - number of calls to a function per executable binary (not per PID!)
+ *    - allows to see where an optimization would be beneficial for a given
+ *      application
+ *  - graph of CPU time spend in functions per executable binary
+ *    - together with the number of calls to this function this allows
+ *      to determine if a kernel optimization would be beneficial / is
+ *      possible for a given application
+ *  - graph of longest running (CPU-time!) function in total
+ *    - may help finding problem cases in the kernel code
+ * - timing statistics for the emul_lock
+ * - graph of longest held (CPU-time!) locks
+ */
+
+#pragma D option dynvarsize=32m
+
+linuxulator*:::entry
+{
+	self->time[probefunc] = vtimestamp;
+	@calls[probeprov, execname, probefunc] = count();
+}
+
+linuxulator*:::return
+/self->time[probefunc] != 0/
+{
+	this->timediff = self->time[probefunc] - vtimestamp;
+
+	@stats[probeprov, execname, probefunc] = quantize(this->timediff);
+	@longest[probeprov, probefunc] = max(this->timediff);
+	
+	self->time[probefunc] = 0;
+}
+
+linuxulator*:::locked
+{
+	self->lock[arg0] = vtimestamp;
+}
+
+linuxulator*:::unlock
+/self->lock[arg0] != 0/
+{
+	this->timediff = self->lock[arg0] - vtimestamp;
+
+	@lockstats[probefunc] = quantize(this->timediff);
+	@longlock[probefunc] = max(this->timediff);
+
+	self->lock[arg0] = 0;
+}
+
+END
+{
+	printf("Number of calls per provider/application/kernel function:");
+	printa(@calls);
+	printf("CPU-timing statistics per provider/application/kernel function (in ns):");
+	printa(@stats);
+	printf("Longest running (CPU-time!) functions per provider (in ns):");
+	printa(@longest);
+	printf("Lock CPU-timing statistics:");
+	printa(@lockstats);
+	printf("Longest running (CPU-time!) locks:");
+	printa(@longlock);
+}
+