tests: test various buffer sizes in misc-bdev-write test

Xen block driver now supports new featute called indirect descriptors.
This feature allows to put more data into each ring cell but it activates
for "long" reads and writes only - longer than 11 pages.

With this patch test by default runs 2 scenarious:
  * 1 page buffers
  * 32 pages buffers

Also introduced command line parameter to specify
size of buffers explicitly.

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

tests/misc-bdev-write.cc

@@ -28,7 +28,7 @@ static void bio_done(struct bio* bio)
 {
     auto err = bio->bio_flags & BIO_ERROR;
     bytes_written += bio->bio_bcount;
-    memory::free_page(bio->bio_data);
+    delete [] (char*) bio->bio_data;
     destroy_bio(bio);
     bio_inflights--;
     if (err) {
@@ -36,28 +36,10 @@ static void bio_done(struct bio* bio)
     }
 }
 
-int main(int argc, char const *argv[])
+void do_test_cycle(struct device *dev, int buf_size_pages, long max_offset)
 {
-    struct device *dev;
-    if (argc < 2) {
-        printf("Usage: %s <dev-name>\n", argv[0]);
-        return 1;
-    }
-
-    if (device_open(argv[1], DO_RDWR, &dev)) {
-        printf("open failed\n");
-        return 1;
-    }
-
-    long max_offset = 0;
-    if (argc > 2) {
-        max_offset = atol(argv[2]);
-    }
-
-    printf("bdev-write test offset limit: %ld byte(s)\n", max_offset);
-
     const std::chrono::seconds test_duration(10);
-    const int buf_size = 4*KB;
+    const int buf_size = buf_size_pages * memory::page_size;
 
     long total = 0;
     long offset = 0;
@@ -65,6 +47,8 @@ int main(int argc, char const *argv[])
     auto test_start = s_clock.now();
     auto end_at = test_start + test_duration;
 
+    printf("Testing with %d page(s) buffers:\n", buf_size_pages);
+
     stat_printer _stat_printer(bytes_written, [] (float bytes_per_second) {
         printf("%.3f Mb/s\n", (float)bytes_per_second / MB);
     }, 1000);
@@ -74,7 +58,7 @@ int main(int argc, char const *argv[])
         bio_inflights++;
         bio->bio_cmd = BIO_WRITE;
         bio->bio_dev = dev;
-        bio->bio_data = memory::alloc_page();
+        bio->bio_data = new char[buf_size];
         bio->bio_offset = offset;
         bio->bio_bcount = buf_size;
         bio->bio_caller1 = bio;
@@ -97,7 +81,42 @@ int main(int argc, char const *argv[])
     _stat_printer.stop();
 
     auto actual_test_duration = to_seconds(test_end - test_start);
-    printf("Wrote %.3f MB in %.2f s = %.3f Mb/s\n", (double) total / MB, actual_test_duration,
-            (double) total / MB / actual_test_duration);
+    printf("Wrote %.3f MB in %.2f s = %.3f Mb/s\n", (double) total / MB,
+            actual_test_duration, (double) total / MB / actual_test_duration);
+}
+
+int main(int argc, char const *argv[])
+{
+    struct device *dev;
+    if (argc < 2) {
+        printf("Usage: %s <dev-name> [max-write-offset] "
+               "[buffer size in pages]\n", argv[0]);
+        return 1;
+    }
+
+    if (device_open(argv[1], DO_RDWR, &dev)) {
+        printf("open failed\n");
+        return 1;
+    }
+
+    long max_offset = 0;
+    if (argc > 2) {
+        max_offset = atol(argv[2]);
+    }
+
+    long buffer_size_pages = 0;
+    if (argc > 3) {
+        buffer_size_pages = atol(argv[3]);
+    }
+
+    printf("bdev-write test offset limit: %ld byte(s)\n", max_offset);
+
+    if (buffer_size_pages == 0) {
+        do_test_cycle(dev, 32, max_offset);
+        do_test_cycle(dev, 1, max_offset);
+    } else {
+        do_test_cycle(dev, buffer_size_pages, max_offset);
+    }
+
     return 0;
-}
\ No newline at end of file
+}