2 * Copyright 2017 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 // @author Andrei Alexandrescu (andrei.alexandrescu@fb.com)
19 #include <folly/Benchmark.h>
20 #include <folly/Foreach.h>
21 #include <folly/json.h>
22 #include <folly/String.h>
25 #include <boost/regex.hpp>
35 DEFINE_bool(benchmark, false, "Run benchmarks.");
36 DEFINE_bool(json, false, "Output in JSON format.");
41 "Only benchmarks whose names match this regex will be run.");
46 "Minimum # of microseconds we'll accept for each benchmark.");
51 "Minimum # of iterations we'll try for each benchmark.");
56 "Maximum # of iterations we'll try for each benchmark.");
61 "Maximum # of seconds we'll spend on each benchmark.");
65 BenchmarkSuspender::NanosecondsSpent BenchmarkSuspender::nsSpent;
67 typedef function<detail::TimeIterPair(unsigned int)> BenchmarkFun;
70 vector<tuple<string, string, BenchmarkFun>>& benchmarks() {
71 static vector<tuple<string, string, BenchmarkFun>> _benchmarks;
75 #define FB_FOLLY_GLOBAL_BENCHMARK_BASELINE fbFollyGlobalBenchmarkBaseline
76 #define FB_STRINGIZE_X2(x) FB_STRINGIZE(x)
78 // Add the global baseline
79 BENCHMARK(FB_FOLLY_GLOBAL_BENCHMARK_BASELINE) {
87 size_t getGlobalBenchmarkBaselineIndex() {
88 const char *global = FB_STRINGIZE_X2(FB_FOLLY_GLOBAL_BENCHMARK_BASELINE);
89 auto it = std::find_if(
92 [global](const tuple<string, string, BenchmarkFun> &v) {
93 return get<1>(v) == global;
96 CHECK(it != benchmarks().end());
97 return size_t(std::distance(benchmarks().begin(), it));
100 #undef FB_STRINGIZE_X2
101 #undef FB_FOLLY_GLOBAL_BENCHMARK_BASELINE
103 void detail::addBenchmarkImpl(const char* file, const char* name,
105 benchmarks().emplace_back(file, name, std::move(fun));
109 * Given a bunch of benchmark samples, estimate the actual run time.
111 static double estimateTime(double * begin, double * end) {
114 // Current state of the art: get the minimum. After some
115 // experimentation, it seems taking the minimum is the best.
116 return *min_element(begin, end);
119 static double runBenchmarkGetNSPerIteration(const BenchmarkFun& fun,
120 const double globalBaseline) {
121 // They key here is accuracy; too low numbers means the accuracy was
122 // coarse. We up the ante until we get to at least minNanoseconds
124 static uint64_t resolutionInNs = 0;
125 if (!resolutionInNs) {
127 CHECK_EQ(0, clock_getres(CLOCK_REALTIME, &ts));
128 CHECK_EQ(0, ts.tv_sec) << "Clock sucks.";
129 CHECK_LT(0, ts.tv_nsec) << "Clock too fast for its own good.";
130 CHECK_EQ(1, ts.tv_nsec) << "Clock too coarse, upgrade your kernel.";
131 resolutionInNs = ts.tv_nsec;
133 // We choose a minimum minimum (sic) of 100,000 nanoseconds, but if
134 // the clock resolution is worse than that, it will be larger. In
135 // essence we're aiming at making the quantization noise 0.01%.
136 static const auto minNanoseconds =
137 max<uint64_t>(FLAGS_bm_min_usec * 1000UL,
138 min<uint64_t>(resolutionInNs * 100000, 1000000000ULL));
140 // We do measurements in several epochs and take the minimum, to
141 // account for jitter.
142 static const unsigned int epochs = 1000;
143 // We establish a total time budget as we don't want a measurement
144 // to take too long. This will curtail the number of actual epochs.
145 const uint64_t timeBudgetInNs = FLAGS_bm_max_secs * 1000000000ULL;
147 CHECK_EQ(0, clock_gettime(CLOCK_REALTIME, &global));
149 double epochResults[epochs] = { 0 };
150 size_t actualEpochs = 0;
152 for (; actualEpochs < epochs; ++actualEpochs) {
153 const auto maxIters = FLAGS_bm_max_iters;
154 for (unsigned int n = FLAGS_bm_min_iters; n < maxIters; n *= 2) {
155 auto const nsecsAndIter = fun(n);
156 if (nsecsAndIter.first < minNanoseconds) {
159 // We got an accurate enough timing, done. But only save if
160 // smaller than the current result.
161 epochResults[actualEpochs] = max(0.0, double(nsecsAndIter.first) /
162 nsecsAndIter.second - globalBaseline);
163 // Done with the current epoch, we got a meaningful timing.
167 CHECK_EQ(0, clock_gettime(CLOCK_REALTIME, &now));
168 if (detail::timespecDiff(now, global) >= timeBudgetInNs) {
169 // No more time budget available.
175 // If the benchmark was basically drowned in baseline noise, it's
176 // possible it became negative.
177 return max(0.0, estimateTime(epochResults, epochResults + actualEpochs));
185 static const ScaleInfo kTimeSuffixes[] {
186 { 365.25 * 24 * 3600, "years" },
187 { 24 * 3600, "days" },
199 static const ScaleInfo kMetricSuffixes[] {
200 { 1E24, "Y" }, // yotta
201 { 1E21, "Z" }, // zetta
202 { 1E18, "X" }, // "exa" written with suffix 'X' so as to not create
203 // confusion with scientific notation
204 { 1E15, "P" }, // peta
205 { 1E12, "T" }, // terra
206 { 1E9, "G" }, // giga
207 { 1E6, "M" }, // mega
208 { 1E3, "K" }, // kilo
210 { 1E-3, "m" }, // milli
211 { 1E-6, "u" }, // micro
212 { 1E-9, "n" }, // nano
213 { 1E-12, "p" }, // pico
214 { 1E-15, "f" }, // femto
215 { 1E-18, "a" }, // atto
216 { 1E-21, "z" }, // zepto
217 { 1E-24, "y" }, // yocto
221 static string humanReadable(double n, unsigned int decimals,
222 const ScaleInfo* scales) {
223 if (std::isinf(n) || std::isnan(n)) {
224 return folly::to<string>(n);
227 const double absValue = fabs(n);
228 const ScaleInfo* scale = scales;
229 while (absValue < scale[0].boundary && scale[1].suffix != nullptr) {
233 const double scaledValue = n / scale->boundary;
234 return stringPrintf("%.*f%s", decimals, scaledValue, scale->suffix);
237 static string readableTime(double n, unsigned int decimals) {
238 return humanReadable(n, decimals, kTimeSuffixes);
241 static string metricReadable(double n, unsigned int decimals) {
242 return humanReadable(n, decimals, kMetricSuffixes);
245 static void printBenchmarkResultsAsTable(
246 const vector<tuple<string, string, double> >& data) {
248 static const unsigned int columns = 76;
250 // Compute the longest benchmark name
251 size_t longestName = 0;
252 FOR_EACH_RANGE (i, 1, benchmarks().size()) {
253 longestName = max(longestName, get<1>(benchmarks()[i]).size());
256 // Print a horizontal rule
257 auto separator = [&](char pad) {
258 puts(string(columns, pad).c_str());
261 // Print header for a file
262 auto header = [&](const string& file) {
264 printf("%-*srelative time/iter iters/s\n",
265 columns - 28, file.c_str());
269 double baselineNsPerIter = numeric_limits<double>::max();
272 for (auto& datum : data) {
273 auto file = get<0>(datum);
274 if (file != lastFile) {
280 string s = get<1>(datum);
285 bool useBaseline /* = void */;
290 baselineNsPerIter = get<2>(datum);
293 s.resize(columns - 29, ' ');
294 auto nsPerIter = get<2>(datum);
295 auto secPerIter = nsPerIter / 1E9;
296 auto itersPerSec = (secPerIter == 0)
297 ? std::numeric_limits<double>::infinity()
300 // Print without baseline
301 printf("%*s %9s %7s\n",
302 static_cast<int>(s.size()), s.c_str(),
303 readableTime(secPerIter, 2).c_str(),
304 metricReadable(itersPerSec, 2).c_str());
306 // Print with baseline
307 auto rel = baselineNsPerIter / nsPerIter * 100.0;
308 printf("%*s %7.2f%% %9s %7s\n",
309 static_cast<int>(s.size()), s.c_str(),
311 readableTime(secPerIter, 2).c_str(),
312 metricReadable(itersPerSec, 2).c_str());
318 static void printBenchmarkResultsAsJson(
319 const vector<tuple<string, string, double> >& data) {
320 dynamic d = dynamic::object;
321 for (auto& datum: data) {
322 d[std::get<1>(datum)] = std::get<2>(datum) * 1000.;
325 printf("%s\n", toPrettyJson(d).c_str());
328 static void printBenchmarkResults(
329 const vector<tuple<string, string, double> >& data) {
332 printBenchmarkResultsAsJson(data);
334 printBenchmarkResultsAsTable(data);
338 void runBenchmarks() {
339 CHECK(!benchmarks().empty());
341 vector<tuple<string, string, double>> results;
342 results.reserve(benchmarks().size() - 1);
344 std::unique_ptr<boost::regex> bmRegex;
345 if (!FLAGS_bm_regex.empty()) {
346 bmRegex.reset(new boost::regex(FLAGS_bm_regex));
349 // PLEASE KEEP QUIET. MEASUREMENTS IN PROGRESS.
351 size_t baselineIndex = getGlobalBenchmarkBaselineIndex();
353 auto const globalBaseline =
354 runBenchmarkGetNSPerIteration(get<2>(benchmarks()[baselineIndex]), 0);
355 FOR_EACH_RANGE (i, 0, benchmarks().size()) {
356 if (i == baselineIndex) {
359 double elapsed = 0.0;
360 if (get<1>(benchmarks()[i]) != "-") { // skip separators
361 if (bmRegex && !boost::regex_search(get<1>(benchmarks()[i]), *bmRegex)) {
364 elapsed = runBenchmarkGetNSPerIteration(get<2>(benchmarks()[i]),
367 results.emplace_back(get<0>(benchmarks()[i]),
368 get<1>(benchmarks()[i]), elapsed);
371 // PLEASE MAKE NOISE. MEASUREMENTS DONE.
373 printBenchmarkResults(results);