Add manualBench function for tests that measure their own time

Author: Henry Qin

cwrapper/perf_wrapper.cc

@@ -22,6 +22,10 @@ Statistics
 bench(void (*function)(void), int numIterations) {
     return PerfUtils::bench(function, numIterations);
 }
+Statistics
+manualBench(void (*function)(uint64_t*), int numIterations) {
+    return PerfUtils::manualBench(function, numIterations);
+}
 
 #ifdef __cplusplus
 }

cwrapper/perf_wrapper.h

@@ -25,6 +25,7 @@ extern "C" {
 
 typedef struct Statistics Statistics;
 Statistics bench(void (*function)(void), int numIterations);
+Statistics manualBench(void (*function)(uint64_t*), int numIterations);
 
 #ifdef __cplusplus
 }

cwrapper/perf_wrapper_test.c

@@ -33,13 +33,24 @@ uint64_t half(uint64_t n) {
     return n / 2;
 }
 
+void fixedPerformance(uint64_t* N) {
+    *N = 7;
+}
+
 int
 main() {
     Statistics stats = bench(fiveHundredCycles, 100000);
     stats = transformStatistics(stats, half);
     if (stats.count == 100000 && stats.count > stats.min) {
-        puts(GREEN("perf_wrapper_test PASSED"));
+        puts(GREEN("perf_wrapper_test::bench PASSED"));
+    } else {
+        puts(RED("perf_wrapper_test::bench FAILED"));
+    }
+
+    stats = manualBench(fixedPerformance, 100000);
+    if (stats.count == 100000 && stats.average == 7 && stats.median == 7 && stats.min == 7 && stats.max == 7 && stats.stddev == 0) {
+        puts(GREEN("perf_wrapper_test::manualBench PASSED"));
     } else {
-        puts(RED("perf_wrapper FAILED"));
+        puts(RED("perf_wrapper_test::manualBench FAILED"));
     }
 }

src/Perf.cc

@@ -37,6 +37,19 @@ namespace PerfUtils {
             latencies[i] = Cycles::rdtsc() - startTime;
         }
 
+        Statistics stats = computeStatistics(latencies, numIterations);
+        delete[] latencies;
+        return stats;
+    }
+    Statistics manualBench(void (*function)(uint64_t*), int numIterations) {
+        uint64_t* latencies = new uint64_t[numIterations];
+
+        // Page in the memory
+        memset(latencies, 0, numIterations * sizeof(uint64_t));
+        for (int i = 0; i < numIterations; i++) {
+            function(&latencies[i]);
+        }
+
         Statistics stats = computeStatistics(latencies, numIterations);
         delete[] latencies;
         return stats;

src/Perf.h

@@ -15,4 +15,5 @@
 #include "Stats.h"
 namespace PerfUtils {
     Statistics bench(void (*function)(void), int numIterations);
+    Statistics manualBench(void (*function)(uint64_t*), int numIterations);
 }

src/PerfTest.cc

@@ -17,6 +17,7 @@
 
 #include <fcntl.h>
 #include <string.h>
+#include <stdlib.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 
@@ -30,8 +31,22 @@ void fixedCycles(int N) {
     }
 }
 
+void fixedPerformance(uint64_t* N) {
+    *N = 7;
+}
+
 TEST(PerfTest, bench) {
     Statistics stats = PerfUtils::bench([]() {fixedCycles(500);}, 100000);
     EXPECT_EQ(100000, stats.count);
     EXPECT_LE(20, stats.min);
 }
+
+TEST(PerfTest, manualBench) {
+    Statistics stats = PerfUtils::manualBench(fixedPerformance, 100000);
+    EXPECT_EQ(100000, stats.count);
+    EXPECT_EQ(7, stats.average);
+    EXPECT_EQ(7, stats.median);
+    EXPECT_EQ(7, stats.min);
+    EXPECT_EQ(7, stats.max);
+    EXPECT_EQ(0, stats.stddev);
+}