XSync does not guarantee that XRENDER based rendering really finished.

Apparently lots of compositing operations may be still queued and
the benchmark could report much smaller test execution times than
they actually were.

So try to read from all the surfaces in order to ensure that the
rendering is done and all the pending operations finished for them.

1 files changed, 23 insertions, 1 deletions

diff --git a/main.c b/main.c
index ab9ccde..1dc0660 100644
--- a/main.c
+++ b/main.c
@@ -24,6 +24,7 @@ void          xrender_surf_blend(Display *disp, Xrender_Surf *src, Xrender_Surf
 void populate_from_file(Display *disp, Xrender_Surf *rs, char *file);
 void main_loop(void);
 void setup_window(void);
+void sync_after_test(void);
 
 int               win_w = 320;
 int               win_h = 320;
@@ -49,7 +50,7 @@ time_test(char *description, void (*func) (void))
    printf("Test: %s\n", description);
    t1 = get_time();
    for (i = 0; i < REPS; i++) func();
-   XSync(disp, False);
+   sync_after_test();
    t2 = get_time();
    t = t2 - t1;
    printf("Time: %3.3f sec.\n", t);
@@ -187,6 +188,27 @@ Imlib_Image   im_win = NULL;
 Imlib_Image   im_img = NULL;
 
 void
+touch_drawable(Display *disp, Drawable draw)
+{
+   XImage *image = image = XGetImage(disp, draw, 0, 0, 1, 1, 0xffffffff, ZPixmap);
+   if (image)
+      XDestroyImage(image);
+}
+
+/*
+ * Try to read from all the surfaces in order to ensure that the
+ * rendering is done and all the pending operations finished for them.
+ */
+void
+sync_after_test()
+{
+   touch_drawable(disp, surf_win->draw);
+   touch_drawable(disp, surf_off->draw);
+   touch_drawable(disp, surf_img->draw);
+   XSync(disp, False);
+}
+
+void
 test_over_x(void)
 {
    int x, y;