[libc-commits] [libc] [libc] Use Atomics in GPU Benchmarks (PR #98842)

[Joseph Huber via libc-commits]

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@@ -12,60 +13,113 @@ namespace LIBC_NAMESPACE_DECL {
 namespace benchmarks {
 
 FixedVector<Benchmark *, 64> benchmarks;
-cpp::array<BenchmarkResult, 1024> results;
 
 void Benchmark::add_benchmark(Benchmark *benchmark) {
   benchmarks.push_back(benchmark);
 }
 
-BenchmarkResult
-reduce_results(const cpp::array<BenchmarkResult, 1024> &results) {
-  BenchmarkResult result;
-  uint64_t cycles_sum = 0;
-  double standard_deviation_sum = 0;
-  uint64_t min = UINT64_MAX;
-  uint64_t max = 0;
-  uint32_t samples_sum = 0;
-  uint32_t iterations_sum = 0;
-  clock_t time_sum = 0;
-  uint64_t num_threads = gpu::get_num_threads();
-  for (uint64_t i = 0; i < num_threads; i++) {
-    BenchmarkResult current_result = results[i];
-    cycles_sum += current_result.cycles;
-    standard_deviation_sum += current_result.standard_deviation;
-    min = cpp::min(min, current_result.min);
-    max = cpp::max(max, current_result.max);
-    samples_sum += current_result.samples;
-    iterations_sum += current_result.total_iterations;
-    time_sum += current_result.total_time;
+struct AtomicBenchmarkSums {
+  cpp::Atomic<uint64_t> cycles_sum = 0;
+  cpp::Atomic<uint64_t> standard_deviation_sum = 0;
+  cpp::Atomic<uint64_t> min = UINT64_MAX;
+  cpp::Atomic<uint64_t> max = 0;
+  cpp::Atomic<uint32_t> samples_sum = 0;
+  cpp::Atomic<uint32_t> iterations_sum = 0;
+  cpp::Atomic<clock_t> time_sum = 0;
+  cpp::Atomic<uint64_t> active_threads = 0;
+
+  void reset() {
+    active_threads.store(0, cpp::MemoryOrder::RELAXED);
+    cycles_sum.store(0, cpp::MemoryOrder::RELAXED);
+    standard_deviation_sum.store(0, cpp::MemoryOrder::RELAXED);
+    min.store(UINT64_MAX, cpp::MemoryOrder::RELAXED);
+    max.store(0, cpp::MemoryOrder::RELAXED);
+    samples_sum.store(0, cpp::MemoryOrder::RELAXED);
+    iterations_sum.store(0, cpp::MemoryOrder::RELAXED);
+    time_sum.store(0, cpp::MemoryOrder::RELAXED);
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jhuber6 wrote:

Needs a release fence.

https://github.com/llvm/llvm-project/pull/98842