xref: /llvm-project/libc/benchmarks/gpu/LibcGpuBenchmark.cpp (revision deb6b45c32687275a6d4e24326ffc9700f8ae52c)
1 #include "LibcGpuBenchmark.h"
2 #include "src/__support/CPP/algorithm.h"
3 #include "src/__support/CPP/array.h"
4 #include "src/__support/CPP/atomic.h"
5 #include "src/__support/CPP/string.h"
6 #include "src/__support/FPUtil/sqrt.h"
7 #include "src/__support/GPU/utils.h"
8 #include "src/__support/fixedvector.h"
9 #include "src/__support/macros/config.h"
10 #include "src/stdio/printf.h"
11 #include "src/stdlib/srand.h"
12 #include "src/time/gpu/time_utils.h"
13 
14 namespace LIBC_NAMESPACE_DECL {
15 namespace benchmarks {
16 
17 FixedVector<Benchmark *, 64> benchmarks;
18 
19 void Benchmark::add_benchmark(Benchmark *benchmark) {
20   benchmarks.push_back(benchmark);
21 }
22 
23 struct AtomicBenchmarkSums {
24   cpp::Atomic<uint64_t> cycles_sum = 0;
25   cpp::Atomic<uint64_t> standard_deviation_sum = 0;
26   cpp::Atomic<uint64_t> min = UINT64_MAX;
27   cpp::Atomic<uint64_t> max = 0;
28   cpp::Atomic<uint32_t> samples_sum = 0;
29   cpp::Atomic<uint32_t> iterations_sum = 0;
30   cpp::Atomic<clock_t> time_sum = 0;
31   cpp::Atomic<uint64_t> active_threads = 0;
32 
33   void reset() {
34     cpp::atomic_thread_fence(cpp::MemoryOrder::RELEASE);
35     active_threads.store(0, cpp::MemoryOrder::RELAXED);
36     cycles_sum.store(0, cpp::MemoryOrder::RELAXED);
37     standard_deviation_sum.store(0, cpp::MemoryOrder::RELAXED);
38     min.store(UINT64_MAX, cpp::MemoryOrder::RELAXED);
39     max.store(0, cpp::MemoryOrder::RELAXED);
40     samples_sum.store(0, cpp::MemoryOrder::RELAXED);
41     iterations_sum.store(0, cpp::MemoryOrder::RELAXED);
42     time_sum.store(0, cpp::MemoryOrder::RELAXED);
43     cpp::atomic_thread_fence(cpp::MemoryOrder::RELEASE);
44   }
45 
46   void update(const BenchmarkResult &result) {
47     cpp::atomic_thread_fence(cpp::MemoryOrder::RELEASE);
48     active_threads.fetch_add(1, cpp::MemoryOrder::RELAXED);
49 
50     cycles_sum.fetch_add(result.cycles, cpp::MemoryOrder::RELAXED);
51     standard_deviation_sum.fetch_add(
52         static_cast<uint64_t>(result.standard_deviation),
53         cpp::MemoryOrder::RELAXED);
54 
55     // Perform a CAS loop to atomically update the min
56     uint64_t orig_min = min.load(cpp::MemoryOrder::RELAXED);
57     while (!min.compare_exchange_strong(
58         orig_min, cpp::min(orig_min, result.min), cpp::MemoryOrder::ACQUIRE,
59         cpp::MemoryOrder::RELAXED))
60       ;
61 
62     // Perform a CAS loop to atomically update the max
63     uint64_t orig_max = max.load(cpp::MemoryOrder::RELAXED);
64     while (!max.compare_exchange_strong(
65         orig_max, cpp::max(orig_max, result.max), cpp::MemoryOrder::ACQUIRE,
66         cpp::MemoryOrder::RELAXED))
67       ;
68 
69     samples_sum.fetch_add(result.samples, cpp::MemoryOrder::RELAXED);
70     iterations_sum.fetch_add(result.total_iterations,
71                              cpp::MemoryOrder::RELAXED);
72     time_sum.fetch_add(result.total_time, cpp::MemoryOrder::RELAXED);
73     cpp::atomic_thread_fence(cpp::MemoryOrder::RELEASE);
74   }
75 };
76 
77 AtomicBenchmarkSums all_results;
78 constexpr auto GREEN = "\033[32m";
79 constexpr auto RESET = "\033[0m";
80 
81 void print_results(Benchmark *b) {
82   BenchmarkResult result;
83   cpp::atomic_thread_fence(cpp::MemoryOrder::RELEASE);
84   int num_threads = all_results.active_threads.load(cpp::MemoryOrder::RELAXED);
85   result.cycles =
86       all_results.cycles_sum.load(cpp::MemoryOrder::RELAXED) / num_threads;
87   result.standard_deviation =
88       all_results.standard_deviation_sum.load(cpp::MemoryOrder::RELAXED) /
89       num_threads;
90   result.min = all_results.min.load(cpp::MemoryOrder::RELAXED);
91   result.max = all_results.max.load(cpp::MemoryOrder::RELAXED);
92   result.samples =
93       all_results.samples_sum.load(cpp::MemoryOrder::RELAXED) / num_threads;
94   result.total_iterations =
95       all_results.iterations_sum.load(cpp::MemoryOrder::RELAXED) / num_threads;
96   const uint64_t duration_ns =
97       all_results.time_sum.load(cpp::MemoryOrder::RELAXED) / num_threads;
98   const uint64_t duration_us = duration_ns / 1000;
99   const uint64_t duration_ms = duration_ns / (1000 * 1000);
100   uint64_t converted_duration = duration_ns;
101   const char *time_unit;
102   if (duration_ms != 0) {
103     converted_duration = duration_ms;
104     time_unit = "ms";
105   } else if (duration_us != 0) {
106     converted_duration = duration_us;
107     time_unit = "us";
108   } else {
109     converted_duration = duration_ns;
110     time_unit = "ns";
111   }
112   result.total_time = converted_duration;
113   // result.total_time =
114   //     all_results.time_sum.load(cpp::MemoryOrder::RELAXED) / num_threads;
115   cpp::atomic_thread_fence(cpp::MemoryOrder::RELEASE);
116 
117   LIBC_NAMESPACE::printf(
118       "%-24s |%8ld |%8ld |%8ld |%11d |%14ld %2s |%9ld |%9d |\n",
119       b->get_test_name().data(), result.cycles, result.min, result.max,
120       result.total_iterations, result.total_time, time_unit,
121       static_cast<uint64_t>(result.standard_deviation), num_threads);
122 }
123 
124 void print_header() {
125   LIBC_NAMESPACE::printf("%s", GREEN);
126   LIBC_NAMESPACE::printf("Running Suite: %-10s\n",
127                          benchmarks[0]->get_suite_name().data());
128   LIBC_NAMESPACE::printf("%s", RESET);
129   cpp::string titles =
130       "Benchmark                |  Cycles |     Min |     Max | "
131       "Iterations | Time / Iteration |   Stddev |  Threads |\n";
132   LIBC_NAMESPACE::printf(titles.data());
133 
134   cpp::string separator(titles.size(), '-');
135   separator[titles.size() - 1] = '\n';
136   LIBC_NAMESPACE::printf(separator.data());
137 }
138 
139 void Benchmark::run_benchmarks() {
140   uint64_t id = gpu::get_thread_id();
141 
142   if (id == 0) {
143     print_header();
144     LIBC_NAMESPACE::srand(gpu::processor_clock());
145   }
146 
147   gpu::sync_threads();
148 
149   for (Benchmark *b : benchmarks) {
150     if (id == 0)
151       all_results.reset();
152 
153     gpu::sync_threads();
154     if (b->num_threads == static_cast<uint32_t>(-1) || id < b->num_threads) {
155       auto current_result = b->run();
156       all_results.update(current_result);
157     }
158     gpu::sync_threads();
159 
160     if (id == 0)
161       print_results(b);
162   }
163   gpu::sync_threads();
164 }
165 
166 BenchmarkResult benchmark(const BenchmarkOptions &options,
167                           cpp::function<uint64_t(void)> wrapper_func) {
168   BenchmarkResult result;
169   RuntimeEstimationProgression rep;
170   uint32_t total_iterations = 0;
171   uint32_t iterations = options.initial_iterations;
172   if (iterations < 1u)
173     iterations = 1;
174 
175   uint32_t samples = 0;
176   uint64_t total_time = 0;
177   uint64_t best_guess = 0;
178   uint64_t cycles_squared = 0;
179   uint64_t min = UINT64_MAX;
180   uint64_t max = 0;
181 
182   uint64_t overhead = UINT64_MAX;
183   int overhead_iterations = 10;
184   for (int i = 0; i < overhead_iterations; i++)
185     overhead = cpp::min(overhead, LIBC_NAMESPACE::overhead());
186 
187   for (int64_t time_budget = options.max_duration; time_budget >= 0;) {
188     uint64_t sample_cycles = 0;
189     const clock_t start = static_cast<double>(clock());
190     for (uint32_t i = 0; i < iterations; i++) {
191       auto wrapper_intermediate = wrapper_func();
192       uint64_t current_result = wrapper_intermediate - overhead;
193       max = cpp::max(max, current_result);
194       min = cpp::min(min, current_result);
195       sample_cycles += current_result;
196     }
197     const clock_t end = clock();
198     const clock_t duration_ns =
199         ((end - start) * 1000 * 1000 * 1000) / CLOCKS_PER_SEC;
200     total_time += duration_ns;
201     time_budget -= duration_ns;
202     samples++;
203     cycles_squared += sample_cycles * sample_cycles;
204 
205     total_iterations += iterations;
206     const double change_ratio =
207         rep.compute_improvement({iterations, sample_cycles});
208     best_guess = rep.current_estimation;
209 
210     if (samples >= options.max_samples || iterations >= options.max_iterations)
211       break;
212     if (total_time >= options.min_duration && samples >= options.min_samples &&
213         total_iterations >= options.min_iterations &&
214         change_ratio < options.epsilon)
215       break;
216 
217     iterations *= options.scaling_factor;
218   }
219   result.cycles = best_guess;
220   result.standard_deviation = fputil::sqrt<double>(
221       static_cast<double>(cycles_squared) / total_iterations -
222       static_cast<double>(best_guess * best_guess));
223   result.min = min;
224   result.max = max;
225   result.samples = samples;
226   result.total_iterations = total_iterations;
227   result.total_time = total_time / total_iterations;
228   return result;
229 };
230 
231 } // namespace benchmarks
232 } // namespace LIBC_NAMESPACE_DECL
233