cairo-perf-diff: Use median not minimum to report differences

Ideally, the minimum value would indicate the best possible performance,
but I've encountered situations where a bogus minimum value gets lodged
into the cached results for some reason, (and yet doesn't also get
discarded as an outlier). The downside of that situation is that running
more iterations never changes the result, so it's hard to fix the problem,
(resulting in cairo-perf-diff feeling just plain broken as more runs
change nothing).

So let's try using the median time instead.

1 files changed, 5 insertions, 5 deletions

diff --git a/perf/cairo-perf-diff-files.c b/perf/cairo-perf-diff-files.c
index 8b6292a40..e5383793b 100644
--- a/perf/cairo-perf-diff-files.c
+++ b/perf/cairo-perf-diff-files.c
@@ -536,11 +536,11 @@ cairo_perf_report_diff (cairo_perf_report_t			*old,
 	diffs[num_diffs].new = n;
 	if (args->use_ms) {
 	    diffs[num_diffs].speedup =
-		(double) (o->stats.min_ticks / o->stats.ticks_per_ms)
-		       / (n->stats.min_ticks / n->stats.ticks_per_ms);
+		(double) (o->stats.median_ticks / o->stats.ticks_per_ms)
+		       / (n->stats.median_ticks / n->stats.ticks_per_ms);
 	} else {
 	    diffs[num_diffs].speedup =
-		(double) o->stats.min_ticks / n->stats.min_ticks;
+		(double) o->stats.median_ticks / n->stats.median_ticks;
 	}
 	num_diffs++;
 
@@ -591,9 +591,9 @@ cairo_perf_report_diff (cairo_perf_report_t			*old,
 	printf ("%5s-%-4s %26s-%-3d  %6.2f %4.2f%% -> %6.2f %4.2f%%: %5.2fx ",
 		diff->old->backend, diff->old->content,
 		diff->old->name, diff->old->size,
-		diff->old->stats.min_ticks / diff->old->stats.ticks_per_ms,
+		diff->old->stats.median_ticks / diff->old->stats.ticks_per_ms,
 		diff->old->stats.std_dev * 100,
-		diff->new->stats.min_ticks / diff->new->stats.ticks_per_ms,
+		diff->new->stats.median_ticks / diff->new->stats.ticks_per_ms,
 		diff->new->stats.std_dev * 100,
 		change);