perf timechart: Add a power-only mode

For doing work on the Linux power management components, I need to
make long (30+ seconds) traces. Currently, this then results in a
HUGE svg file, with mostly process data that isn't interesting.

This patch adds a --power-only mode to perf timechart that only
outputs the CPU power section of the SVG; this significantly
reduces the size of the SVG file, making even 30+ second traces
viewable with inkscape.

As a minor tweak for the same effect, the minimum text size is
decreased; current inkscape cannot zoom in deep enough to show text
this small, but it reduces inkscape compute time.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: peterz@infradead.org
LKML-Reference: <20090924154013.0675ab71@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/util/svghelper.c b/tools/perf/util/svghelper.c
index a778fd0..856655d 100644
--- a/tools/perf/util/svghelper.c
+++ b/tools/perf/util/svghelper.c
@@ -28,7 +28,7 @@
 
 int svg_page_width = 1000;
 
-#define MIN_TEXT_SIZE 0.001
+#define MIN_TEXT_SIZE 0.01
 
 static u64 total_height;
 static FILE *svgfile;
@@ -217,6 +217,18 @@
 		}
 		fclose(file);
 	}
+
+	/* CPU type */
+	file = fopen("/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies", "r");
+	if (file) {
+		while (fgets(buf, 255, file)) {
+			unsigned int freq;
+			freq = strtoull(buf, NULL, 10);
+			if (freq > max_freq)
+				max_freq = freq;
+		}
+		fclose(file);
+	}
 	return cpu_m;
 }