True Sharing

std::atomic<int> counter{0};

# Run in 4 threads
for (int i = 0; i < 100'000; ++i) {
  counter.fetch_add(1);
}

var counter = std.atomic.Value(i32).init(0);

// Run in 4 threads
for (0..100_000) |_| {
    _ = counter.fetchAdd(1, .monotonic);
}

std::atomic<int> counter{0};

# Run in 4 threads
int local = 0;
for (int i = 0; i < 100'000; ++i) {
  local++;
}
counter.fetch_add(local);

var counter = std.atomic.Value(i32).init(0);

// Run in 4 threads
var local: i32 = 0;
for (0..100_000) |_| {
    local += 1;
}
_ = counter.fetchAdd(local, .monotonic);