perf stat: Print stalled cycles percentage

Print:

           611,527 cycles
           400,553 instructions             # (  0.71 instructions per cycle )
            77,809 stalled-cycles           # ( 12.71% of all cycles )

        0.000610987  seconds time elapsed

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Link: http://lkml.kernel.org/n/tip-fd6x8r1cpyb6zhlrc4ix8m45@git.kernel.org

tools/perf/builtin-stat.c

@@ -442,15 +442,15 @@ static void abs_printout(int cpu, struct perf_evsel *evsel, double avg)
 		if (total)
 			ratio = avg / total;
 
-		fprintf(stderr, " # %10.3f IPC  ", ratio);
+		fprintf(stderr, " # ( %4.2f instructions per cycle )", ratio);
 	} else if (perf_evsel__match(evsel, HARDWARE, HW_BRANCH_MISSES) &&
 			runtime_branches_stats[cpu].n != 0) {
 		total = avg_stats(&runtime_branches_stats[cpu]);
 
 		if (total)
 			ratio = avg * 100 / total;
 
-		fprintf(stderr, " # %10.3f %%    ", ratio);
+		fprintf(stderr, " # %10.3f %%", ratio);
 
 	} else if (runtime_nsecs_stats[cpu].n != 0) {
 		total = avg_stats(&runtime_nsecs_stats[cpu]);
@@ -459,6 +459,13 @@ static void abs_printout(int cpu, struct perf_evsel *evsel, double avg)
 			ratio = 1000.0 * avg / total;
 
 		fprintf(stderr, " # %10.3f M/sec", ratio);
+	} else if (perf_evsel__match(evsel, HARDWARE, HW_STALLED_CYCLES)) {
+		total = avg_stats(&runtime_cycles_stats[cpu]);
+
+		if (total)
+			ratio = avg / total * 100.0;
+
+		fprintf(stderr, " # (%5.2f%% of all cycles )", ratio);
 	}
 }