1 files changed, 29 insertions, 6 deletions

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index bec64a9e741..7ce65f52415 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -196,6 +196,7 @@ static bool			csv_output			= false;
 static bool			group				= false;
 static const char		*output_name			= NULL;
 static FILE			*output				= NULL;
+static int			output_fd;
 
 static volatile int done = 0;
 
@@ -253,8 +254,13 @@ static double avg_stats(struct stats *stats)
  */
 static double stddev_stats(struct stats *stats)
 {
-	double variance = stats->M2 / (stats->n - 1);
-	double variance_mean = variance / stats->n;
+	double variance, variance_mean;
+
+	if (!stats->n)
+		return 0.0;
+
+	variance = stats->M2 / (stats->n - 1);
+	variance_mean = variance / stats->n;
 
 	return sqrt(variance_mean);
 }
@@ -489,6 +495,8 @@ static int run_perf_stat(int argc __used, const char **argv)
 	if (forks) {
 		close(go_pipe[1]);
 		wait(&status);
+		if (WIFSIGNALED(status))
+			psignal(WTERMSIG(status), argv[0]);
 	} else {
 		while(!done) sleep(1);
 	}
@@ -522,7 +530,7 @@ static void print_noise_pct(double total, double avg)
 
 	if (csv_output)
 		fprintf(output, "%s%.2f%%", csv_sep, pct);
-	else
+	else if (pct)
 		fprintf(output, "  ( +-%6.2f%% )", pct);
 }
 
@@ -1080,6 +1088,8 @@ static const struct option options[] = {
 	OPT_STRING('o', "output", &output_name, "file",
 		    "output file name"),
 	OPT_BOOLEAN(0, "append", &append_file, "append to the output file"),
+	OPT_INTEGER(0, "log-fd", &output_fd,
+		    "log output to fd, instead of stderr"),
 	OPT_END()
 };
 
@@ -1166,6 +1176,10 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
 	if (output_name && strcmp(output_name, "-"))
 		output = NULL;
 
+	if (output_name && output_fd) {
+		fprintf(stderr, "cannot use both --output and --log-fd\n");
+		usage_with_options(stat_usage, options);
+	}
 	if (!output) {
 		struct timespec tm;
 		mode = append_file ? "a" : "w";
@@ -1177,18 +1191,27 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
 		}
 		clock_gettime(CLOCK_REALTIME, &tm);
 		fprintf(output, "# started on %s\n", ctime(&tm.tv_sec));
+	} else if (output_fd != 2) {
+		mode = append_file ? "a" : "w";
+		output = fdopen(output_fd, mode);
+		if (!output) {
+			perror("Failed opening logfd");
+			return -errno;
+		}
 	}
 
-	if (csv_sep)
+	if (csv_sep) {
 		csv_output = true;
-	else
+		if (!strcmp(csv_sep, "\\t"))
+			csv_sep = "\t";
+	} else
 		csv_sep = DEFAULT_SEPARATOR;
 
 	/*
 	 * let the spreadsheet do the pretty-printing
 	 */
 	if (csv_output) {
-		/* User explicitely passed -B? */
+		/* User explicitly passed -B? */
 		if (big_num_opt == 1) {
 			fprintf(stderr, "-B option not supported with -x\n");
 			usage_with_options(stat_usage, options);