Pad Away the False Sharing

Difficulty

Asked at Jump Trading, XTX Markets

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Language: C++23Padded

#include <atomic>
#include <cstdint>
#include <cstddef>
#include <new>
#include <thread>
#include <vector>

// ...
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// ...
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// ...
template <std::size_t Threads>
struct Naked {
    std::atomic<long long> counters[Threads]{};

    void bump(std::size_t which) { counters[which].fetch_add(1, std::memory_order_relaxed); }
    long long total() const {
        long long sum = 0;
        for (std::size_t i = 0; i < Threads; ++i) sum += counters[i].load(std::memory_order_relaxed);
        return sum;
    }
};

// ...
// ...
// ...
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// ...
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template <std::size_t Threads>
struct Padded {
    static constexpr std::size_t kLine = 64;

    void bump(std::size_t which) {
        // ...
        (void)which;
    }

    long long total() const {
        // ...
        return 0;
    }

    std::size_t stride() const {
        // ...
        return 0;
    }

    // ...
};

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