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Linux 进度调度测试

Linux 进度调度测试

作者: 蓝笔头 | 来源:发表于2021-07-20 19:08 被阅读0次

调度器的参数

参数简介：

  • sched_min_granularity_ns：CFS 设定了进程占用 CPU 的最小时间值，sched_min_granularity_ns，正在 CPU 上运行的进程如果不足这个时间是不可以被调离 CPU 的。
  • sched_latency_ns：设定一个调度周期（sched_latency_ns），目标是让每个进程在这个周期内至少有机会运行一次，换一种说法就是每个进程等待 CPU 的时间最长不超过这个调度周期；然后根据进程的数量，大家平分这个调度周期内的 CPU 使用权，由于进程的优先级即 nice 值不同，分割调度周期的时候要加权。

如果进程数量太多的话，就会造成 CPU 时间片太小，如果小于 sched_min_granularity_ns 的话就以 sched_min_granularity_ns 为准；而调度周期也随之不再遵守 sched_latency_ns，而是以（sched_min_granularity_ns * 进程数量）的乘积为准。

实际配置：

$ uname -a
Linux dev.xxx.net 4.19.0-17-amd64 #1 SMP Debian 4.19.194-1 (2021-06-10) x86_64 GNU/Linux
$ cat /proc/sys/kernel/sched_min_granularity_ns
3000000
$ cat /proc/sys/kernel/sched_latency_ns
24000000

单位转换：

  • 1 (ms) = 1000 * 1000 (ns)
  • 3000000 (ns) = 3(ms)
  • 24000000 (ns) = 24(ms)

测试代码

import java.time.LocalDateTime;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;


public class TestThread {
    private static int threadCount = 10;
    private static int calcCount = 10000;

    public static void main(String[] args) throws InterruptedException {
        if (args.length >= 1) {
            threadCount = Integer.parseInt(args[0]);
        }
        if (args.length >= 2) {
            calcCount = Integer.parseInt(args[1]);
        }

        System.out.println(LocalDateTime.now());
        System.out.println(Runtime.getRuntime().availableProcessors());
        ScheduledExecutorService executorService = Executors.newScheduledThreadPool(threadCount);
        for (int i = 0; i < threadCount; ++i) {
            String task = "task_" + i;
            System.out.println(LocalDateTime.now() + " -- [" + task + "] 分配线程");
            executorService.scheduleAtFixedRate(() -> spin(task, calcCount), 0, 500, TimeUnit.MILLISECONDS);
        }
    }

    public static void spin(String task, int count) {
        System.out.println(LocalDateTime.now() + " -- [" + task + "] spin 开始, 当前线程:" + Thread.currentThread().getName());
        long startTime = System.currentTimeMillis();
        long tempStartTime = startTime;

        long num = 1;
        long max = 0;
        max = Math.max(System.currentTimeMillis() - tempStartTime, max);
        for (int i = 0; i < count; ++ i) {
            num = num * 3;
            max = Math.max(System.currentTimeMillis() - tempStartTime, max);

            tempStartTime = System.currentTimeMillis();
        }
        long stopTime = System.currentTimeMillis();
        System.out.println(LocalDateTime.now() + " -- [" + task + "] spend time = " + (stopTime - startTime) + "(ms) num = "
            + num + " 当前线程:" + Thread.currentThread().getName() + "max = " + max);

    }
}

jmx 参数：

-Dcom.sun.management.jmxremote.port=12345 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false

线程数量：1

$ java TestThread 1 50000
2021-07-20T21:22:04.818
1
2021-07-20T21:22:04.825 -- [task_0] 分配线程
2021-07-20T21:22:04.847 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:04.866 -- [task_0] spend time = 19(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:22:05.343 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:05.357 -- [task_0] spend time = 13(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:22:05.843 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:05.851 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:22:06.343 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:06.351 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:22:06.843 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:06.851 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:22:07.343 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:07.350 -- [task_0] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:22:07.842 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:07.850 -- [task_0] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:22:08.343 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:08.351 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:22:08.843 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:08.850 -- [task_0] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:22:09.343 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:22:09.351 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1

通过 1 个线程的测试，可以发现执行 50000 次循环大概要 8ms。

线程数量：3

$ java TestThread 3 50000
2021-07-20T21:27:14.824
1
2021-07-20T21:27:14.831 -- [task_0] 分配线程
2021-07-20T21:27:14.849 -- [task_1] 分配线程
2021-07-20T21:27:14.850 -- [task_2] 分配线程
2021-07-20T21:27:14.850 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:27:14.851 -- [task_1] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:27:14.854 -- [task_2] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:27:14.883 -- [task_0] spend time = 32(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:27:14.883 -- [task_1] spend time = 32(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:27:14.886 -- [task_2] spend time = 32(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:27:15.350 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:27:15.350 -- [task_1] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:27:15.350 -- [task_2] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:27:15.403 -- [task_2] spend time = 53(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:27:15.404 -- [task_0] spend time = 54(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:27:15.405 -- [task_1] spend time = 55(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:27:15.849 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:27:15.850 -- [task_1] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:27:15.850 -- [task_2] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:27:15.857 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:27:15.860 -- [task_2] spend time = 10(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:27:15.860 -- [task_1] spend time = 10(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:27:16.349 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:27:16.350 -- [task_1] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:27:16.350 -- [task_2] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:27:16.357 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:27:16.358 -- [task_1] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:27:16.358 -- [task_2] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:27:16.849 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:27:16.850 -- [task_1] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:27:16.850 -- [task_2] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:27:16.856 -- [task_0] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:27:16.858 -- [task_1] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:27:16.858 -- [task_2] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:27:17.349 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:27:17.350 -- [task_1] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:27:17.350 -- [task_2] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:27:17.356 -- [task_0] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:27:17.357 -- [task_1] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:27:17.358 -- [task_2] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1

3 个线程，一个线程执行 8ms，符合 sched_latency_ns = 24ms 的值，说明在 sched_latency_ns 范围内每个线程都会执行一次，即不会被切换上下文。

后面输出的日志也说明了这一点。

线程数量：4

$ java TestThread 4 50000
2021-07-20T21:30:23.714
1
2021-07-20T21:30:23.721 -- [task_0] 分配线程
2021-07-20T21:30:23.740 -- [task_1] 分配线程
2021-07-20T21:30:23.741 -- [task_2] 分配线程
2021-07-20T21:30:23.742 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:30:23.743 -- [task_1] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:30:23.744 -- [task_3] 分配线程
2021-07-20T21:30:23.747 -- [task_2] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:30:23.750 -- [task_3] spin 开始, 当前线程:pool-1-thread-4
2021-07-20T21:30:23.778 -- [task_0] spend time = 36(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:30:23.779 -- [task_3] spend time = 29(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 1
2021-07-20T21:30:23.781 -- [task_1] spend time = 38(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:30:23.781 -- [task_2] spend time = 34(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:30:24.241 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:30:24.241 -- [task_1] spin 开始, 当前线程:pool-1-thread-4
2021-07-20T21:30:24.242 -- [task_2] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:30:24.245 -- [task_3] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:30:24.288 -- [task_1] spend time = 47(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 1
2021-07-20T21:30:24.299 -- [task_0] spend time = 58(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:30:24.299 -- [task_2] spend time = 57(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:30:24.300 -- [task_3] spend time = 55(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:30:24.740 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:30:24.741 -- [task_1] spin 开始, 当前线程:pool-1-thread-4
2021-07-20T21:30:24.742 -- [task_2] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:30:24.745 -- [task_3] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:30:24.749 -- [task_0] spend time = 9(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:30:24.752 -- [task_1] spend time = 11(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 1
2021-07-20T21:30:24.754 -- [task_2] spend time = 12(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:30:24.755 -- [task_3] spend time = 10(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:30:25.240 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:30:25.241 -- [task_1] spin 开始, 当前线程:pool-1-thread-4
2021-07-20T21:30:25.241 -- [task_2] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:30:25.245 -- [task_3] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:30:25.248 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:30:25.249 -- [task_1] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 1
2021-07-20T21:30:25.254 -- [task_2] spend time = 12(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:30:25.257 -- [task_3] spend time = 12(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 5
2021-07-20T21:30:25.740 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:30:25.741 -- [task_1] spin 开始, 当前线程:pool-1-thread-4
2021-07-20T21:30:25.742 -- [task_2] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:30:25.745 -- [task_3] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:30:25.748 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:30:25.750 -- [task_2] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:30:25.750 -- [task_1] spend time = 9(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 1
2021-07-20T21:30:25.753 -- [task_3] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:30:26.240 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:30:26.241 -- [task_1] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:30:26.242 -- [task_2] spin 开始, 当前线程:pool-1-thread-4
2021-07-20T21:30:26.245 -- [task_3] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:30:26.248 -- [task_0] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:30:26.249 -- [task_1] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:30:26.255 -- [task_2] spend time = 13(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 5
2021-07-20T21:30:26.258 -- [task_3] spend time = 12(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:30:26.740 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:30:26.741 -- [task_1] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:30:26.742 -- [task_2] spin 开始, 当前线程:pool-1-thread-4
2021-07-20T21:30:26.745 -- [task_3] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:30:26.749 -- [task_1] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:30:26.749 -- [task_2] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 1
2021-07-20T21:30:26.752 -- [task_3] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:30:26.754 -- [task_0] spend time = 13(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:30:27.240 -- [task_0] spin 开始, 当前线程:pool-1-thread-1
2021-07-20T21:30:27.241 -- [task_1] spin 开始, 当前线程:pool-1-thread-4
2021-07-20T21:30:27.242 -- [task_2] spin 开始, 当前线程:pool-1-thread-3
2021-07-20T21:30:27.245 -- [task_3] spin 开始, 当前线程:pool-1-thread-2
2021-07-20T21:30:27.248 -- [task_0] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-1max = 1
2021-07-20T21:30:27.249 -- [task_2] spend time = 7(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 1
2021-07-20T21:30:27.253 -- [task_3] spend time = 8(ms) num = -246746203963084735 当前线程:pool-1-thread-2max = 1
2021-07-20T21:30:27.257 -- [task_1] spend time = 16(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 8

4 个线程，一个线程执行 8ms，大于 sched_latency_ns = 24ms 的值，说明在 sched_latency_ns 范围内每个线程无法执行都一次，因此会被切换上下文。

日志中的 max=5 和 max=8 说明发生了线程切换。

...
2021-07-20T21:30:25.257 -- [task_3] spend time = 12(ms) num = -246746203963084735 当前线程:pool-1-thread-3max = 5
...
2021-07-20T21:30:26.255 -- [task_2] spend time = 13(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 5
...
2021-07-20T21:30:27.257 -- [task_1] spend time = 16(ms) num = -246746203963084735 当前线程:pool-1-thread-4max = 8
...

系统负载

$ uptime
 10:31:23 up 262 days, 13:01,  2 users,  load average: 0.02, 0.05, 0.21

$ java TestThread 500

$ uptime
 10:34:04 up 262 days, 13:04,  2 users,  load average: 0.84, 0.31, 0.27

参考

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