output header to STDERR in measure_syscall

This hopefully helps a bit to clarify the output.

1 files changed, 2 insertions, 0 deletions

diff --git a/bin/null_call.c b/bin/null_call.c
index 61c4629..d714e77 100644
--- a/bin/null_call.c
+++ b/bin/null_call.c
@@ -48,6 +48,8 @@ int main(int argc, char **argv)
                         "%lus and %luns.\n",
                         (unsigned long) sleep_time.tv_sec,
                         (unsigned long) sleep_time.tv_nsec);
+                fprintf(stderr, "%10s, %10s, %10s, %10s, %10s, %10s\n",
+                        "pre", "in kernel", "post", "entry", "exit", "total");
                 do {
                         time_null_call();
                 } while (nanosleep(&sleep_time, NULL) == 0);