Should you care about an extra indirection when updating atomics?

no.cc

#include <stdio.h>
#include <stdlib.h>

#include <atomic>
#include <chrono>

std::chrono::milliseconds direct(int iters) {
    auto start = std::chrono::system_clock::now();
    auto val = new std::atomic<int>[1];

    for (int i = 0; i < iters; ++ i) {
        val[0].fetch_add(1);
    }

    delete [] val;
    auto end = std::chrono::system_clock::now();
    return std::chrono::duration_cast<std::chrono::milliseconds>(end - start);
}

std::chrono::milliseconds indirect(int iters) {
    auto start = std::chrono::system_clock::now();

    auto val = new std::atomic<int>*[1];
    val[0] = new std::atomic<int>;

    for (int i = 0; i < iters; ++ i) {
        val[0]->fetch_add(1);
    }

    delete val[0];
    delete [] val;

    auto end = std::chrono::system_clock::now();
    return std::chrono::duration_cast<std::chrono::milliseconds>(end - start);
}

int main(int argc, char **argv) {
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <iterations>\n", argv[0]);
        exit(1);
    }

    int iters = atoi(argv[1]);
    auto dir = direct(iters);
    auto ind = indirect(iters);

    printf("%d iters: %lld direct, %lld indirect\n", iters, dir.count(), ind.count());

    return 0;
}