perf timechart: Add backtrace support to CPU info

Add backtrace info to the CPU usage timechart.
Signed-off-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ramkumar Ramachandra <artagnon@gmail.com>
Link: http://lkml.kernel.org/r/1385995056-20158-2-git-send-email-stfomichev@yandex-team.ruSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-timechart.c

@@ -837,8 +837,14 @@ static void draw_cpu_usage(struct timechart *tchart)
 		while (c) {
 			sample = c->samples;
 			while (sample) {
-				if (sample->type == TYPE_RUNNING)
-					svg_process(sample->cpu, sample->start_time, sample->end_time, "sample", c->comm);
+				if (sample->type == TYPE_RUNNING) {
+					svg_process(sample->cpu,
+						    sample->start_time,
+						    sample->end_time,
+						    "sample",
+						    c->comm,
+						    sample->backtrace);
+				}
 
 				sample = sample->next;
 			}

tools/perf/util/svghelper.c

@@ -285,7 +285,7 @@ void svg_cpu_box(int cpu, u64 __max_freq, u64 __turbo_freq)
 	fprintf(svgfile, "</g>\n");
 }
 
-void svg_process(int cpu, u64 start, u64 end, const char *type, const char *name)
+void svg_process(int cpu, u64 start, u64 end, const char *type, const char *name, const char *backtrace)
 {
 	double width;
 
@@ -295,6 +295,8 @@ void svg_process(int cpu, u64 start, u64 end, const char *type, const char *name
 
 	fprintf(svgfile, "<g transform=\"translate(%4.8f,%4.8f)\">\n", time2pixels(start), cpu2y(cpu));
 	fprintf(svgfile, "<title>%s %s</title>\n", name, time_to_string(end - start));
+	if (backtrace)
+		fprintf(svgfile, "<desc>Switched because:\n%s</desc>\n", backtrace);
 	fprintf(svgfile, "<rect x=\"0\" width=\"%4.8f\" y=\"0\" height=\"%4.1f\" class=\"%s\"/>\n",
 		time2pixels(end)-time2pixels(start), SLOT_MULT+SLOT_HEIGHT, type);
 	width = time2pixels(end)-time2pixels(start);

tools/perf/util/svghelper.h

@@ -11,7 +11,7 @@ extern void svg_waiting(int Yslot, int cpu, u64 start, u64 end, const char *back
 extern void svg_cpu_box(int cpu, u64 max_frequency, u64 turbo_frequency);
 
 
-extern void svg_process(int cpu, u64 start, u64 end, const char *type, const char *name);
+extern void svg_process(int cpu, u64 start, u64 end, const char *type, const char *name, const char *backtrace);
 extern void svg_cstate(int cpu, u64 start, u64 end, int type);
 extern void svg_pstate(int cpu, u64 start, u64 end, u64 freq);