1 files changed, 74 insertions, 0 deletions
diff --git a/measure.c b/measure.c
new file mode 100644
index 0000000..ef06c5b
--- /dev/null
+++ b/measure.c
@@ -0,0 +1,74 @@
+/* See LICENSE file for copyright and license details. */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+
+
+#ifndef CAPACITY
+# define CAPACITY (1 << 20)
+#endif
+
+
+int
+main(int argc, char *argv[])
+{
+	int fd, n = 0, m = 150000;
+	ssize_t r;
+	size_t sum = 0, totsum = 0;
+	struct timespec start, end;
+	double rate;
+
+	if (!argc)
+		*argv = "measure";
+
+	if (argc > 1)
+		m = atoi(argv[1]);
+
+	fd = open("/dev/null", O_WRONLY);
+	if (fd < 0)
+		goto fail;
+
+	usleep(10000L);
+	if (argc < 2 && fcntl(STDIN_FILENO, F_GETPIPE_SZ) == CAPACITY)
+		m = 10;
+
+	if (clock_gettime(CLOCK_MONOTONIC, &start))
+		goto fail;
+	for (;;) {
+		r = splice(STDIN_FILENO, NULL, fd, NULL, SSIZE_MAX, 0);
+		if (r <= 0) {
+			if (r < 0)
+				goto fail;
+			goto done;
+		}
+		sum += (size_t)r;
+		if (++n == m) {
+			if (clock_gettime(CLOCK_MONOTONIC, &end))
+				goto fail;
+			n = 0;
+			start.tv_sec  = end.tv_sec  - start.tv_sec;
+			start.tv_nsec = end.tv_nsec - start.tv_nsec;
+			rate = (double)start.tv_nsec;
+			rate /= 1000000000.;
+			rate += start.tv_sec;
+			rate = (double)sum / rate;
+			rate /= 1000000000.;
+			totsum += sum;
+			sum = 0;
+			dprintf(STDERR_FILENO, "  %lf GB/s\033[K\n\033[A", rate);
+			start = end;
+		}
+	}
+
+done:
+	return 0;
+
+fail:
+	perror(*argv);
+	return 1;
+}