larsch · September 9, 2018 10:23 · Sep 9, 2018
diff --git a/termbench.c b/termbench.c
@@ -0,0 +1,55 @@
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <time.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+void writestr(int fd, const char* str) {
+  write(fd, str, strlen(str));
+}
+
+#define LINES_PER_WRITE 128
+#define LINE_BUFFER 80
+#define TOTAL_BUFFER (LINE_BUFFER*LINES_PER_WRITE)
+
+int main() {
+  char str[LINES_PER_WRITE];
+  int fd = fileno(stdout);
+  memset(str, 'x', LINE_BUFFER);
+  str[LINE_BUFFER-1] = '\n';
+
+  char* buffer = malloc(TOTAL_BUFFER);
+  for (int i = 0; i < LINES_PER_WRITE; ++i)
+    memcpy(buffer + i * LINE_BUFFER, str, LINE_BUFFER);
+
+  int n = 128;
+  for (int i = 0; i < 999; ++i) {
+    struct timespec before;
+    struct timespec after;
+    clock_gettime(CLOCK_MONOTONIC, &before);
+    writestr(fd, "\x1b[?1049h");
+    for (int i = 0; i < n; ++i) {
+      write(fd, buffer, TOTAL_BUFFER);
+    }
+    fsync(fd);
+    clock_gettime(CLOCK_MONOTONIC, &after);
+    writestr(fd, "\x1b[?1049l");
+
+    uint64_t delta_secs = after.tv_sec - before.tv_sec;
+    int64_t delta_nsecs = after.tv_nsec - before.tv_nsec;
+    if (delta_nsecs < 0) {
+      delta_nsecs += 1000000000;
+      delta_secs -= 1;
+    }
+    delta_nsecs += delta_secs * 1000000000;
+    int lines_written = LINES_PER_WRITE * n;
+    printf("lines=%d nsecs=l%ld lines/sec=%llu\n", n, delta_nsecs, (lines_written * 1000000000ull) / delta_nsecs);
+    if (delta_nsecs > 1000000000)
+      break;
+    n = (n * 1050000000ull) / delta_nsecs;
+  }
+
+  free(buffer);
+  return 0;
+}