perf script: Allow time to be displayed in nanoseconds

Add option --ns to display time to 9 decimal places. That is useful in
some cases, for example when using Intel PT cycle accurate mode.

Signed-off-by: Adrian Hunter <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/perf-script.txt

···
 --full-source-path::
 	Show the full path for source files for srcline output.
 
+--ns::
+	Use 9 decimal places when displaying time (i.e. show the nanoseconds)
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-script-perl[1],

tools/perf/builtin-script.c

···
 static bool			latency_format;
 static bool			system_wide;
 static bool			print_flags;
+static bool			nanosecs;
 static const char		*cpu_list;
 static DECLARE_BITMAP(cpu_bitmap, MAX_NR_CPUS);
 
···
 		secs = nsecs / NSECS_PER_SEC;
 		nsecs -= secs * NSECS_PER_SEC;
 		usecs = nsecs / NSECS_PER_USEC;
-		printf("%5lu.%06lu: ", secs, usecs);
+		if (nanosecs)
+			printf("%5lu.%09llu: ", secs, nsecs);
+		else
+			printf("%5lu.%06lu: ", secs, usecs);
 	}
 }
 
···
 	OPT_BOOLEAN('\0', "show-switch-events", &script.show_switch_events,
 		    "Show context switch events (if recorded)"),
 	OPT_BOOLEAN('f', "force", &file.force, "don't complain, do it"),
+	OPT_BOOLEAN(0, "ns", &nanosecs,
+		    "Use 9 decimal places when displaying time"),
 	OPT_CALLBACK_OPTARG(0, "itrace", &itrace_synth_opts, NULL, "opts",
 			    "Instruction Tracing options",
 			    itrace_parse_synth_opts),