perf timechart: Get number of CPUs from perf header

Print all CPUs, even if there were no events (use perf header to get
number of CPUs).

This is required to support topology in the next patch.
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/1385995056-20158-4-git-send-email-stfomichev@yandex-team.ruSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-timechart.c

@@ -531,12 +531,10 @@ static int process_sample_event(struct perf_tool *tool,
 			tchart->last_time = sample->time;
 	}
 
-	if (sample->cpu > tchart->numcpus)
-		tchart->numcpus = sample->cpu;
-
 	if (evsel->handler != NULL) {
 		tracepoint_handler f = evsel->handler;
-		return f(tchart, evsel, sample, cat_backtrace(event, sample, machine));
+		return f(tchart, evsel, sample,
+			 cat_backtrace(event, sample, machine));
 	}
 
 	return 0;
@@ -1038,8 +1036,6 @@ static void write_svg_file(struct timechart *tchart, const char *filename)
 	int count;
 	int thresh = TIME_THRESH;
 
-	tchart->numcpus++;
-
 	if (tchart->power_only)
 		tchart->proc_num = 0;
 
@@ -1069,6 +1065,25 @@ static void write_svg_file(struct timechart *tchart, const char *filename)
 	svg_close();
 }
 
+static int process_header(struct perf_file_section *section __maybe_unused,
+			  struct perf_header *ph,
+			  int feat,
+			  int fd __maybe_unused,
+			  void *data)
+{
+	struct timechart *tchart = data;
+
+	switch (feat) {
+	case HEADER_NRCPUS:
+		tchart->numcpus = ph->env.nr_cpus_avail;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
 static int __cmd_timechart(struct timechart *tchart, const char *output_name)
 {
 	const struct perf_evsel_str_handler power_tracepoints[] = {
@@ -1094,6 +1109,11 @@ static int __cmd_timechart(struct timechart *tchart, const char *output_name)
 	if (session == NULL)
 		return -ENOMEM;
 
+	(void)perf_header__process_sections(&session->header,
+					    perf_data_file__fd(session->file),
+					    tchart,
+					    process_header);
+
 	if (!perf_session__has_traces(session, "timechart record"))
 		goto out_delete;