perf script: Align event name properly

Adding code to align event names, so we get aligned output in case of
multiple events with different names.

Before:
  $ perf script
  :13757 13757 163918.230829: cpu/mem-snp-none/P: ffff88085f20d010
  :13757 13757 163918.230832: cpu/mem-loads,ldlat=30/P:     7f5a5f719f00
  :13757 13757 163918.230835: cpu/mem-loads,ldlat=30/P:     7f5a5f719f00
  :13758 13758 163918.230838: cpu/mem-snp-none/P: ffff88085f4ad810
  :13758 13758 163918.154093: cpu/mem-stores/P: ffff88085bb53f28
  :13757 13757 163918.155264: cpu/mem-snp-hitm/P:           601080
  ...

After:
  $ perf script
  :13757 13757 163918.228831:       cpu/mem-snp-none/P: ffffffff81a841c0
  :13757 13757 163918.228834: cpu/mem-loads,ldlat=30/P:     7f5a5f719f08
  :13757 13757 163918.228837: cpu/mem-loads,ldlat=30/P:     7f5a5f719f08
  :13758 13758 163918.228837:       cpu/mem-snp-none/P: ffff88085f4ad800
  :13758 13758 163918.154093:         cpu/mem-stores/P: ffff88085bb53f28
  :13757 13757 163918.155264:       cpu/mem-snp-hitm/P:           601080
  ...
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Noel Grandin <noelgrandin@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1452158050-28061-9-git-send-email-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-script.c

@@ -617,9 +617,24 @@ struct perf_script {
 	bool			allocated;
 	struct cpu_map		*cpus;
 	struct thread_map	*threads;
+	int			name_width;
 };
 
-static void process_event(struct perf_script *script __maybe_unused, union perf_event *event,
+static int perf_evlist__max_name_len(struct perf_evlist *evlist)
+{
+	struct perf_evsel *evsel;
+	int max = 0;
+
+	evlist__for_each(evlist, evsel) {
+		int len = strlen(perf_evsel__name(evsel));
+
+		max = MAX(len, max);
+	}
+
+	return max;
+}
+
+static void process_event(struct perf_script *script, union perf_event *event,
 			  struct perf_sample *sample, struct perf_evsel *evsel,
 			  struct addr_location *al)
 {
@@ -636,7 +651,12 @@ static void process_event(struct perf_script *script __maybe_unused, union perf_
 
 	if (PRINT_FIELD(EVNAME)) {
 		const char *evname = perf_evsel__name(evsel);
-		printf("%s: ", evname ? evname : "[unknown]");
+
+		if (!script->name_width)
+			script->name_width = perf_evlist__max_name_len(script->session->evlist);
+
+		printf("%*s: ", script->name_width,
+		       evname ? evname : "[unknown]");
 	}
 
 	if (print_flags)