Question

我有一个让我疯狂的Contiki应用程序。

我必须计算Tmote Sky的精力消耗。我正在使用energest，这是我在能耗估算函数中使用的一段代码，它定期被称为：

lpm_time = energest_type_time(ENERGEST_TYPE_LPM);
cpu_time = energest_type_time(ENERGEST_TYPE_CPU);
rx_time = energest_type_time(ENERGEST_TYPE_LISTEN);
tx_time = energest_type_time(ENERGEST_TYPE_TRANSMIT);
lpm = lpm_time - prev_times.lpm_time;
cpu = cpu_time - prev_times.cpu_time;
rx = rx_time - prev_times.rx_time;
tx = tx_time - prev_times.tx_time;

consumed_energy = (I_LPM * lpm + I_CPU * cpu + I_RX * rx + I_TX * tx) * VOLTS / RTIMER_ARCH_SECOND;  /* mJ = mA * seconds * volts */

/*printf("lpm %lu, cpu %lu, rx %lu, tx %lu, prl %lu, prc %lu, prr %lu, prt %lu\n",
       lpm_time, cpu_time, rx_time, tx_time, prev_times.lpm_time, prev_times.cpu_time, prev_times.rx_time, prev_times.tx_time);*/

prev_times.lpm_time = lpm_time;
prev_times.cpu_time = cpu_time;
prev_times.rx_time = rx_time;
prev_times.tx_time = tx_time;

问题是只有在启用了现在注释的printf时，应用程序才能正常工作。如果它按原样保持注释，我可以为consumed_energy变量接收无意义的值，或者使用Java Illegal read - out of bounds消息停止COOJA模拟。

为什么会这样？可能是什么原因？这是一件非常奇怪的事情。

提前致谢。

此文件的完整代码如下：

volatile static struct energest_times prev_times;


float update_consumption()
{
    uint32_t lpm_time;
    uint32_t cpu_time;
    uint32_t rx_time;
    uint32_t tx_time;
    uint32_t lpm;
    uint32_t cpu;
    uint32_t rx;
    uint32_t tx;
    float consumed_energy;

    lpm_time = energest_type_time(ENERGEST_TYPE_LPM);
    cpu_time = energest_type_time(ENERGEST_TYPE_CPU);
    rx_time = energest_type_time(ENERGEST_TYPE_LISTEN);
    tx_time = energest_type_time(ENERGEST_TYPE_TRANSMIT);
    lpm = lpm_time - prev_times.lpm_time;
    cpu = cpu_time - prev_times.cpu_time;
    rx = rx_time - prev_times.rx_time;
    tx = tx_time - prev_times.tx_time;

    consumed_energy = (I_LPM * lpm + I_CPU * cpu + I_RX * rx + I_TX * tx) * VOLTS / RTIMER_ARCH_SECOND;  /* mJ = mA * seconds * volts */

    printf("lpm %lu, cpu %lu, rx %lu, tx %lu, prl %lu, prc %lu, prr %lu, prt %lu\n",
            lpm_time, cpu_time, rx_time, tx_time, prev_times.lpm_time, prev_times.cpu_time, prev_times.rx_time, prev_times.tx_time);

    prev_times.lpm_time = lpm_time;
    prev_times.cpu_time = cpu_time;
    prev_times.rx_time = rx_time;
    prev_times.tx_time = tx_time;

    printf("Consumed energy: %ld\n", (int32_t) consumed_energy);

    return consumed_energy;
}

该功能由另一个功能定期调用，每分钟一次。

Answer 1

如果你有多个线程使用非线程安全的库，你可以在Java或C中看到这个。在这种情况下，你有时会得到正确的价值，有时你会得到一半的权利，有时候你会变得毫无意义。

如果您添加printf，例如System.out.printf（）或任何IO或sleep（）或使用调试逐步执行代码，这实际上减慢了您的应用程序速度，因此每个线程在库中花费的时间非常小，从而间接避免冲突。

您使用的是多线程吗？您调用的库/方法是否安全？

如果我删除printf，应用程序将无法正常工作

1 个答案: