寫程序讓CPU佔用率保持正弦函數

導入自 renren

據說是一道微軟的面試題。如題,寫程序,讓Windows的任務管理器中的性能監視器呈現正弦曲線。

正弦曲線 正弦曲線

潛心鑽研良久,得代碼:(java)

public class sincpu {
    private static final int cycle=1024,tick = 256;
    public static void main (String[] args) throws InterruptedException {
        for(int i = 0;;i++){
            work(calcNextSleep(i % cycle));
            sleep(tick - calcNextSleep(i % cycle));
        }
    }

    private static long calcNextSleep(long i){
        return (int)(Math.sin((double)i * 2 * Math.PI / cycle) * tick + tick) / 2;
    }

    private static void sleep (long sleepTime) throws InterruptedException
    {
        if(sleepTime < 2)
            Thread.yield();
        else
            Thread.sleep(sleepTime);
    }

    private static void work (long period) {
        long start = System.currentTimeMillis();
        for(;;){
            Math.sin(1);
            if(System.currentTimeMillis() - start >= period)
                break;
        }
    }
}

多核CPU上測試時要注意關掉一個CPU:

多核CPU上測試
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