1.编译two-loops.c, gcc two-loops.c -pthread，运行两份

baohua@baohua-VirtualBox:~/develop/training/process-courses/day3$ gcc two-loops.c -pthread
baohua@baohua-VirtualBox:~/develop/training/process-courses/day3$ ./a.out &
[1] 13682
baohua@baohua-VirtualBox:~/develop/training/process-courses/day3$ main pid:13682, tid:3075434240
thread pid:13682, tid:3067038528
thread pid:13682, tid:3075431232

baohua@baohua-VirtualBox:~/develop/training/process-courses/day3$ ./a.out &
[2] 13685
baohua@baohua-VirtualBox:~/develop/training/process-courses/day3$ main pid:13685, tid:3075925760
thread pid:13685, tid:3067530048
thread pid:13685, tid:3075922752

top命令观察CPU利用率：

    13682 baohua    20   0   18684    616    552 S  98.4  0.0   1:12.09 a.out
    13685 baohua    20   0   18684    644    580 S  98.1  0.0   1:07.32 a.out 

renice其中之一，再观察CPU利用率

    sudo renice -n -5 -g 13682

      PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
    13682 baohua    15  -5   18684    616    552 S 147.4  0.0   4:52.73 a.out
    13685 baohua    20   0   18684    644    580 S  48.6  0.0   4:12.77 a.out

killall a.out

2.编译two-loops.c, gcc two-loops.c -pthread，运行一份

• top发现其CPU利用率接近200%

• 把它的所有线程设置为SCHED_FIFO

    chrt -f -a -p 50 进程PID
  

• 再观察它的CPU利用率