From 24a0bddf4ae13d8f1fa0436a547de67dcf6d4f2a Mon Sep 17 00:00:00 2001
From: Cory Fields <cory-nospam-@coryfields.com>
Date: Wed, 25 Oct 2017 17:54:05 -0400
Subject: [PATCH] bench: prefer a steady clock if the resolution is no worse

---
 src/bench/bench.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/bench/bench.h b/src/bench/bench.h
index d7037e1f3..d276f4ee9 100644
--- a/src/bench/bench.h
+++ b/src/bench/bench.h
@@ -37,8 +37,15 @@ BENCHMARK(CODE_TO_TIME);
  */
  
 namespace benchmark {
-
-    using clock = std::chrono::high_resolution_clock;
+    // On many systems, the high_resolution_clock offers no better resolution than the steady_clock.
+    // If that's the case, prefer the steady_clock.
+    struct best_clock {
+        using hi_res_clock = std::chrono::high_resolution_clock;
+        using steady_clock = std::chrono::steady_clock;
+        static constexpr bool steady_is_high_res = std::ratio_less_equal<steady_clock::period, hi_res_clock::period>::value;
+        using type = std::conditional<steady_is_high_res, steady_clock, hi_res_clock>::type;
+    };
+    using clock = best_clock::type;
     using time_point = clock::time_point;
     using duration = clock::duration;