tracing: add "power-tracer": C/P state tracer to help power optimization

Impact: new "power-tracer" ftrace plugin

This patch adds a C/P-state ftrace plugin that will generate
detailed statistics about the C/P-states that are being used,
so that we can look at detailed decisions that the C/P-state
code is making, rather than the too high level "average"
that we have today.

An example way of using this is:

 mount -t debugfs none /sys/kernel/debug
 echo cstate > /sys/kernel/debug/tracing/current_tracer
 echo 1 > /sys/kernel/debug/tracing/tracing_enabled
 sleep 1
 echo 0 > /sys/kernel/debug/tracing/tracing_enabled
 cat /sys/kernel/debug/tracing/trace | perl scripts/trace/cstate.pl > out.svg

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 108 insertions, 0 deletions

diff --git a/scripts/trace/power.pl b/scripts/trace/power.pl
new file mode 100644
index 000000000000..4f729b3501e0
--- /dev/null
+++ b/scripts/trace/power.pl
@@ -0,0 +1,108 @@
+#!/usr/bin/perl
+
+# Copyright 2008, Intel Corporation
+#
+# This file is part of the Linux kernel
+#
+# This program file is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the
+# Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program in a file named COPYING; if not, write to the
+# Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor,
+# Boston, MA 02110-1301 USA
+#
+# Authors:
+#       Arjan van de Ven <arjan@linux.intel.com>
+
+
+#
+# This script turns a cstate ftrace output into a SVG graphic that shows
+# historic C-state information
+#
+#
+#       cat /sys/kernel/debug/tracing/trace | perl power.pl > out.svg
+#
+
+my @styles;
+my $base = 0;
+
+my @pstate_last;
+my @pstate_level;
+
+$styles[0] = "fill:rgb(0,0,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[1] = "fill:rgb(0,255,0);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[2] = "fill:rgb(255,0,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[3] = "fill:rgb(255,255,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[4] = "fill:rgb(255,0,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[5] = "fill:rgb(0,255,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[6] = "fill:rgb(0,128,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[7] = "fill:rgb(0,255,128);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[8] = "fill:rgb(0,25,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+
+
+print "<?xml version=\"1.0\" standalone=\"no\"?> \n";
+print "<svg width=\"10000\" height=\"100%\" version=\"1.1\" xmlns=\"http://www.w3.org/2000/svg\">\n";
+
+my $scale = 30000.0;
+while (<>) {
+        my $line = $_;
+        if ($line =~ /([0-9\.]+)\] CSTATE: Going to C([0-9]) on cpu ([0-9]+) for ([0-9\.]+)/) {
+                if ($base == 0) {
+                        $base = $1;
+                }
+                my $time = $1 - $base;
+                $time = $time * $scale;
+                my $C = $2;
+                my $cpu = $3;
+                my $y = 400 * $cpu;
+                my $duration = $4 * $scale;
+                my $msec = int($4 * 100000)/100.0;
+                my $height = $C * 20;
+                $style = $styles[$C];
+
+                $y = $y + 140 - $height;
+
+                $x2 = $time + 4;
+                $y2 = $y + 4;
+
+
+                print "<rect x=\"$time\" width=\"$duration\" y=\"$y\" height=\"$height\" style=\"$style\"/>\n";
+                print "<text transform=\"translate($x2,$y2) rotate(90)\">C$C $msec</text>\n";
+        }
+        if ($line =~ /([0-9\.]+)\] PSTATE: Going to P([0-9]) on cpu ([0-9]+)/) {
+                my $time = $1 - $base;
+                my $state = $2;
+                my $cpu = $3;
+
+                if (defined($pstate_last[$cpu])) {
+                        my $from = $pstate_last[$cpu];
+                        my $oldstate = $pstate_state[$cpu];
+                        my $duration = ($time-$from) * $scale;
+
+                        $from = $from * $scale;
+                        my $to = $from + $duration;
+                        my $height = 140 - ($oldstate * (140/8));
+
+                        my $y = 400 * $cpu + 200 + $height;
+                        my $y2 = $y+4;
+                        my $style = $styles[8];
+
+                        print "<rect x=\"$from\" y=\"$y\" width=\"$duration\" height=\"5\" style=\"$style\"/>\n";
+                        print "<text transform=\"translate($from,$y2)\">P$oldstate (cpu $cpu)</text>\n";
+                };
+
+                $pstate_last[$cpu] = $time;
+                $pstate_state[$cpu] = $state;
+        }
+}
+
+
+print "</svg>\n";