fix: dont sample warmup with perf

Author: not-matthias

google_benchmark/src/benchmark.cc

@@ -573,9 +573,14 @@ void RunBenchmarks(const std::vector<BenchmarkInstance>& benchmarks,
         codspeed->start_benchmark(runner.GetBenchmarkName());
       }
 
-      measurement_start();
+      // Only start measurement if warmup is done
+      bool measurement_started = false;
+      if (runner.IsWarmupDone()) {
+        measurement_start();
+        measurement_started = true;
+      }
 #endif
-      
+
       runner.DoOneRepetition();
       if (runner.HasRepeatsRemaining()) {
         continue;
@@ -605,7 +610,9 @@ void RunBenchmarks(const std::vector<BenchmarkInstance>& benchmarks,
       }
 
 #ifdef CODSPEED_WALLTIME
-      measurement_stop();
+      if (measurement_started) {
+        measurement_stop();
+      }
 
       if (codspeed != nullptr) {
         codspeed->end_benchmark();

google_benchmark/src/benchmark_runner.h

@@ -74,6 +74,8 @@ class BenchmarkRunner {
 
   IterationCount GetIters() const { return iters; }
 
+  bool IsWarmupDone() const { return warmup_done; }
+
  private:
   RunResults run_results;