False sharing issue with even non atomic data

Author: ashishnegi

falsesharing.cpp

@@ -5,7 +5,7 @@
 namespace false_sharing
 {
     const int N = 1024;
-    std::atomic_int global_nonshared[4096];
+    long global_nonshared[4096];
 
     static void BM_FalseSharing2Global(benchmark::State& state) {
         if (state.thread_index == 0) {
@@ -25,7 +25,7 @@ namespace false_sharing
     }
 
     static void BM_FalseSharing2Local(benchmark::State& state) {
-        std::atomic_int local_nonshared = 0;
+        long local_nonshared = 0;
 
         while (state.KeepRunning()) {
             for (int i = 0; i < N; ++i) {
@@ -41,28 +41,13 @@ namespace false_sharing
     // Register the function as a benchmark
     BENCHMARK(BM_FalseSharing2Global) ARGS(1, 0);
     BENCHMARK(BM_FalseSharing2Global) ARGS(2, 0);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(4, 0);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(8, 0);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(12, 0);
     BENCHMARK(BM_FalseSharing2Global) ARGS(1, 4);
     BENCHMARK(BM_FalseSharing2Global) ARGS(2, 4);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(4, 4);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(8, 4);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(12, 4);
     BENCHMARK(BM_FalseSharing2Global) ARGS(1, 8);
     BENCHMARK(BM_FalseSharing2Global) ARGS(2, 8);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(4, 8);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(8, 8);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(12, 8);
     BENCHMARK(BM_FalseSharing2Global) ARGS(1, 16);
     BENCHMARK(BM_FalseSharing2Global) ARGS(2, 16);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(4, 16);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(8, 16);
-    BENCHMARK(BM_FalseSharing2Global) ARGS(12, 16);
     BENCHMARK(BM_FalseSharing2Local) ARGS(1, 0);
     BENCHMARK(BM_FalseSharing2Local) ARGS(2, 0);
-    BENCHMARK(BM_FalseSharing2Local) ARGS(4, 0);
-    BENCHMARK(BM_FalseSharing2Local) ARGS(8, 0);
-    BENCHMARK(BM_FalseSharing2Local) ARGS(12, 0);
 } // namespace false_sharing