Question

我有以下代码创建一个命名的共享内存段，然后尝试找到其numa节点ID：

    const auto handle = shm_open("/myshm", O_RDWR | O_CREAT, 0666);
    if (-1 == handle) {
        std::cout << "failed to open named shared memory" << std::endl;
        throw;
    }
    constexpr auto size = 32;
    ftruncate(handle, size);
    auto myshm = (void*) mmap(nullptr, size, PROT_READ | PROT_WRITE,
            MAP_SHARED, handle, 0);

    if (MAP_FAILED == myshm) {
        std::cout << errno << std::endl;
        throw;
    }

    // for some reason 0666 does not take effect, chmod it again
    const auto rc = fchmod(handle, 0666);
    if (rc == -1) {
        std::cerr << "Can't change permissions to 0666 on shared mem segment\n" << std::end;
    }

    constexpr uint32_t nPages = std::ceil(size / 4096.0);
    int32_t status[nPages];
    if (0 != move_pages(0, nPages, &myshm, nullptr, status, MPOL_MF_MOVE_ALL)) {
        std::cout << "failed to inquiry  SHM: " << strerror(errno) << std::endl;
    }
    else {
        for (uint32_t i = 0; i < nPages; i++) {
            std::cout << "page " << i << " locate at numa node " << status[i] << std::endl;
        }
    }

奇怪的是我得到failed to inquiry SHM: Operation not permitted

我确实在可执行文件tho上运行sudo setcap 'cap_sys_nice=eip'。

有什么主意吗？

move_pages（）返回非零？

0 个答案: