From d1ac9460c2fbb41620aab27a58e90c3ded8c00f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ren=C3=A9=20Canna=C3=B2?= <rene.cannao@gmail.com>
Date: Mon, 8 Apr 2019 16:51:25 +1000
Subject: [PATCH] Adding microbench for PR1977

---
 microbench/PR1977_bench.cpp | 131 ++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 microbench/PR1977_bench.cpp

diff --git a/microbench/PR1977_bench.cpp b/microbench/PR1977_bench.cpp
new file mode 100644
index 000000000..6efae4507
--- /dev/null
+++ b/microbench/PR1977_bench.cpp
@@ -0,0 +1,131 @@
+#include <cstdio>
+#include <cstdlib>
+#include <iostream>
+
+__thread unsigned int g_seed;
+
+inline int fastrand() {
+    g_seed = (214013*g_seed+2531011);
+    return (g_seed>>16)&0x7FFF;
+}
+
+inline unsigned long long monotonic_time() {
+	struct timespec ts;
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	return (((unsigned long long) ts.tv_sec) * 1000000) + (ts.tv_nsec / 1000);
+}
+
+
+#define NSRV	24
+#define NLOOP	10000000
+
+struct cpu_timer
+{
+	cpu_timer() {
+		begin = monotonic_time();
+	}
+	~cpu_timer()
+	{   
+		unsigned long long end = monotonic_time();
+		std::cerr << double( end - begin ) / 1000000 << " secs.\n" ;
+		begin=end-begin; // here only to make compiler happy
+	};
+	unsigned long long begin;
+};
+
+
+int main(int argc, char** argv) {
+	unsigned int * usedConns = NULL;
+	unsigned int * weights = NULL;
+	unsigned int sum = 0;
+	unsigned int TotalUsedConn = 0;
+
+	srand(monotonic_time());
+	usedConns = (unsigned int *)malloc(NSRV*sizeof(unsigned int));
+	weights = (unsigned int *)malloc(NSRV*sizeof(unsigned int));
+	for (int i=0 ; i < NSRV ; i++ ) {
+		usedConns[i] = 20+rand()%1000;
+		weights[i] = 20+rand()%10000;
+	}
+	for (int N=4; N<=NSRV; N+=4) {
+	std::cerr << "Test with " << N << " servers:" << std::endl;
+	{
+		cpu_timer c;
+		for (int i=0; i<NLOOP; i++) {
+			sum = 0;
+			TotalUsedConn = 0;
+			for (int j=0; j<N; j++) {
+				sum += weights[j];
+				TotalUsedConn += usedConns[j];
+			}
+			unsigned int New_sum=0;
+			unsigned int New_TotalUsedConn=0;
+			for (int j=0; j<N; j++) {
+				unsigned int len = usedConns[j];
+				unsigned int weight = weights[j];
+				if ((len * sum) <= (TotalUsedConn * weight * 1.5 + 1)) {
+					New_sum += weight;
+					New_TotalUsedConn += len;
+				}
+			}
+			unsigned int k;
+			if (New_sum > 32768) {
+				k = rand() % New_sum;
+			} else {
+				k = fastrand() % New_sum;
+			}
+			New_sum = 0;
+			for (int j=0; j<N; j++) {
+				unsigned int len = usedConns[j];
+				unsigned int weight = weights[j];
+				if ((len * sum) <= (TotalUsedConn * weight * 1.5 + 1)) {
+					New_sum += weight;
+					if (k <= New_sum) {
+						break;
+					}
+				}
+			}
+		}
+		std::cerr << "INT test ran in \t";
+	}
+	{
+		cpu_timer c;
+		for (int i=0; i<NLOOP; i++) {
+			double sum = 0;
+			TotalUsedConn = 0;
+			for (int j=0; j<N; j++) {
+				sum += weights[j];
+				TotalUsedConn += usedConns[j];
+			}
+			double New_sum=0;
+			unsigned int New_TotalUsedConn=0;
+			for (int j=0; j<N; j++) {
+				unsigned int len = usedConns[j];
+				unsigned int weight = weights[j];
+				if ((len * sum) <= (TotalUsedConn * weight * 1.5 + 1)) {
+					New_sum += weight;
+					New_TotalUsedConn += len;
+				}
+			}
+			double k;
+			if (New_sum > 32768) {
+				k = drand48() * New_sum;
+			} else {
+				k = fastrand() % (unsigned int)New_sum;
+			}
+			New_sum = 0;
+			for (int j=0; j<N; j++) {
+				unsigned int len = usedConns[j];
+				unsigned int weight = weights[j];
+				if ((len * sum) <= (TotalUsedConn * weight * 1.5 + 1)) {
+					New_sum += weight;
+					if (k <= New_sum) {
+						break;
+					}
+				}
+			}
+		}
+		std::cerr << "DOUBLE test ran in \t";
+	}
+	}
+}