From 7072c544b52774ac5a22835121e8e2747ad61158 Mon Sep 17 00:00:00 2001
From: Gavin Andresen <gavinandresen@gmail.com>
Date: Tue, 29 Sep 2015 17:17:24 -0400
Subject: Support very-fast-running benchmarks

Avoid calling gettimeofday every time through the benchmarking loop, by keeping
track of how long each loop takes and doubling the number of iterations done
between time checks when they take less than 1/16'th of the total elapsed time.
---
 src/bench/Examples.cpp | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 src/bench/Examples.cpp

(limited to 'src/bench/Examples.cpp')

diff --git a/src/bench/Examples.cpp b/src/bench/Examples.cpp
new file mode 100644
index 000000000..b6b020a97
--- /dev/null
+++ b/src/bench/Examples.cpp
@@ -0,0 +1,34 @@
+// Copyright (c) 2015 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "bench.h"
+#include "main.h"
+#include "utiltime.h"
+
+// Sanity test: this should loop ten times, and
+// min/max/average should be close to 100ms.
+static void Sleep100ms(benchmark::State& state)
+{
+    while (state.KeepRunning()) {
+        MilliSleep(100);
+    }
+}
+
+BENCHMARK(Sleep100ms);
+
+// Extremely fast-running benchmark:
+#include <math.h>
+
+volatile double sum = 0.0; // volatile, global so not optimized away
+
+static void Trig(benchmark::State& state)
+{
+    double d = 0.01;
+    while (state.KeepRunning()) {
+        sum += sin(d);
+        d += 0.000001;
+    }
+}
+
+BENCHMARK(Trig);
-- 
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