[babl] babl: add a test iteration multiplier

[Øyvind Kolås <ok src gnome org>]

commit 636ac86e9f5fd9dbc5d062d5394bd32eb2196e72
Author: Øyvind Kolås <pippin gimp org>
Date:   Wed Jan 17 03:57:23 2018 +0100

    babl: add a test iteration multiplier
    
    On my system many of the conversions got measured to costs of 3 4 and 5, these
    makes a big room for measurement errors, to increase reliability the tests are
    now run 4 times - making it a ranking of contenders with fewer collisions.
    
    This will slightly increase incurred delayed on search for conversions.

 babl/babl-fish-path.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/babl/babl-fish-path.c b/babl/babl-fish-path.c
index eb10fe9..d387fa8 100644
--- a/babl/babl-fish-path.c
+++ b/babl/babl-fish-path.c
@@ -26,6 +26,8 @@
 #define BABL_HARD_MAX_PATH_LENGTH  8
 #define BABL_MAX_NAME_LEN          1024
 
+#define BABL_TEST_ITER             4
+
 #ifndef MIN
 #define MIN(a, b) (((a) > (b)) ? (b) : (a))
 #endif
@@ -926,7 +928,7 @@ init_path_instrumentation (FishPathInstrumentation *fpi,
                  fpi->source, fpi->ref_destination,
                  fpi->num_test_pixels);
   ticks_end = babl_ticks ();
-  fpi->reference_cost = ticks_end - ticks_start;
+  fpi->reference_cost = (ticks_end - ticks_start) * BABL_TEST_ITER;
 
   /* transform the reference destination buffer to RGBA */
   _babl_process (fpi->fish_destination_to_rgba,
@@ -1002,6 +1004,7 @@ get_path_instrumentation (FishPathInstrumentation *fpi,
 
   /* calculate this path's view of what the result should be */
   ticks_start = babl_ticks ();
+  for (int i = 0; i < BABL_TEST_ITER; i ++)
   process_conversion_path (path, fpi->source, source_bpp, fpi->destination,
                            dest_bpp, fpi->num_test_pixels);
   ticks_end = babl_ticks ();