1 // Copyright 2017 Google Inc. All Rights Reserved.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "absl/random/internal/nanobenchmark.h"
16
17 #include "absl/log/check.h"
18 #include "absl/log/log.h"
19 #include "absl/strings/numbers.h"
20 #include "absl/strings/str_format.h"
21
22 namespace absl {
23 ABSL_NAMESPACE_BEGIN
24 namespace random_internal_nanobenchmark {
25 namespace {
26
Div(const void *,FuncInput in)27 uint64_t Div(const void*, FuncInput in) {
28 // Here we're measuring the throughput because benchmark invocations are
29 // independent.
30 const int64_t d1 = 0xFFFFFFFFFFll / int64_t(in); // IDIV
31 return d1;
32 }
33
34 template <size_t N>
MeasureDiv(const FuncInput (& inputs)[N])35 void MeasureDiv(const FuncInput (&inputs)[N]) {
36 Result results[N];
37 Params params;
38 params.max_evals = 6; // avoid test timeout
39 const size_t num_results = Measure(&Div, nullptr, inputs, N, results, params);
40 if (num_results == 0) {
41 LOG(WARNING)
42 << "WARNING: Measurement failed, should not happen when using "
43 "PinThreadToCPU unless the region to measure takes > 1 second.";
44 return;
45 }
46 for (size_t i = 0; i < num_results; ++i) {
47 LOG(INFO) << absl::StreamFormat("%5u: %6.2f ticks; MAD=%4.2f%%\n",
48 results[i].input, results[i].ticks,
49 results[i].variability * 100.0);
50 CHECK_NE(results[i].ticks, 0.0f) << "Zero duration";
51 }
52 }
53
RunAll(const int argc,char * argv[])54 void RunAll(const int argc, char* argv[]) {
55 // Avoid migrating between cores - important on multi-socket systems.
56 int cpu = -1;
57 if (argc == 2) {
58 if (!absl::SimpleAtoi(argv[1], &cpu)) {
59 LOG(FATAL) << "The optional argument must be a CPU number >= 0.";
60 }
61 }
62 PinThreadToCPU(cpu);
63
64 // unpredictable == 1 but the compiler doesn't know that.
65 const FuncInput unpredictable = argc != 999;
66 static const FuncInput inputs[] = {unpredictable * 10, unpredictable * 100};
67
68 MeasureDiv(inputs);
69 }
70
71 } // namespace
72 } // namespace random_internal_nanobenchmark
73 ABSL_NAMESPACE_END
74 } // namespace absl
75
main(int argc,char * argv[])76 int main(int argc, char* argv[]) {
77 absl::random_internal_nanobenchmark::RunAll(argc, argv);
78 return 0;
79 }
80