背景：
测试活动中，需要构造cpu打满、磁盘打满、网卡打满的场景
场景1：cpu打满
环境信息：
虚拟机，物理核数16个，每个物理核的虚拟核数1个，虚拟核数16个：
[root@vm10-0-0-8 test_data]# cat /proc/cpuinfo| grep "physical id"| sort| uniq| wc -l
16
[root@vm10-0-0-8 test_data]# cat /proc/cpuinfo| grep "cpu cores"| uniq
cpu cores : 1
[root@vm10-0-0-8 test_data]# cat /proc/cpuinfo| grep "processor"| wc -l
16
top命令查看到当前cpu 占用率：
[root@vm10-0-0-8 test_data]# top
top - 21:20:02 up 16 days, 6:07, 6 users, load average: 10.29, 8.05, 3.80
Tasks: 198 total, 1 running, 197 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.0 us, 0.1 sy, 0.0 ni, 99.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 32778624 total, 18760920 free, 701276 used, 13316428 buff/cache
KiB Swap: 0 total, 0 free, 0 used. 31481428 avail Mem
%Cpu(s):
0.0 us,用户占用率（没有nice调度过）
0.1 sy,系统占用率
0.0 ni,用户空间通过nice调度过的程序cpu占用率
99.9 id,idle，空闲率
0.0 wa, 0.0 hi, 0.0 si, 0.0 st
构造cpu打满的场景：
[root@vm10-0-0-8 test_data]# cat while_1.sh
#!/bin/bash function while_1()
{ while ((1));
do
i=2;
done
} while_1 &
执行while_1.sh后，发现cpu中1个core被打满了：
[root@vm10-0-0-8 test_data]# sh while_1.sh
[root@vm10-0-0-8 test_data]#
[root@vm10-0-0-8 test_data]# ps -ef |grep while_1.sh
root 21553 1 99 21:29 pts/4 00:00:03 sh while_1.sh [root@vm10-0-0-8 test_data]# top
top - 21:29:54 up 16 days, 6:17, 6 users, load average: 1.17, 4.11, 3.58
Tasks: 196 total, 2 running, 194 sleeping, 0 stopped, 0 zombie
%Cpu(s): 4.5 us, 1.7 sy, 0.0 ni, 93.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 32778624 total, 18763900 free, 698328 used, 13316396 buff/cache
KiB Swap: 0 total, 0 free, 0 used. 31484616 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
21553 root 20 0 113176 392 200 R 100.0 0.0 0:20.97 sh
将16个core都打满：
[root@vm10-0-0-8 test_data]# cat run_while.sh
#!/bin/bash function while_1()
{
while ((1));
do
i=2;
done
} function run_while()
{
for ((i=0; i<$1; i++));
do
while_1 &
done
} run_while $1
[root@vm10-0-0-8 test_data]# sh run_while.sh 16 （16是core的数，可自定义）
[root@vm10-0-0-8 test_data]# ps -ef |grep while
root 21751 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21752 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21753 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21754 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21755 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21756 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21757 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21758 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21759 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21760 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21761 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21762 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21763 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21764 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21765 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
root 21766 1 99 21:31 pts/4 00:00:55 sh run_while.sh 16
查看cpu占用清空，idle为零了：
[root@vm10-0-0-8 test_data]# top
top - 21:33:55 up 16 days, 6:21, 6 users, load average: 14.08, 7.45, 4.85
Tasks: 211 total, 17 running, 194 sleeping, 0 stopped, 0 zombie
%Cpu(s): 73.3 us, 26.7 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 32778624 total, 18758856 free, 702964 used, 13316804 buff/cache
KiB Swap: 0 total, 0 free, 0 used. 31479616 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
21761 root 20 0 113176 388 196 R 100.0 0.0 2:05.13 sh
21751 root 20 0 113176 388 196 R 100.0 0.0 2:05.11 sh
21752 root 20 0 113176 388 196 R 100.0 0.0 2:05.13 sh
21753 root 20 0 113176 388 196 R 100.0 0.0 2:05.13 sh
21754 root 20 0 113176 388 196 R 100.0 0.0 2:05.12 sh
21756 root 20 0 113176 388 196 R 100.0 0.0 2:05.13 sh
21758 root 20 0 113176 388 196 R 100.0 0.0 2:05.13 sh
21759 root 20 0 113176 388 196 R 100.0 0.0 2:05.13 sh
21760 root 20 0 113176 388 196 R 100.0 0.0 2:05.13 sh
21762 root 20 0 113176 388 196 R 100.0 0.0 2:05.12 sh
21764 root 20 0 113176 388 192 R 100.0 0.0 2:05.10 sh
21766 root 20 0 113176 388 192 R 100.0 0.0 2:05.13 sh
21755 root 20 0 113176 388 196 R 100.0 0.0 2:05.11 sh
21757 root 20 0 113176 388 196 R 100.0 0.0 2:05.10 sh
21763 root 20 0 113176 388 192 R 100.0 0.0 2:05.11 sh
21765 root 20 0 113176 388 192 R 100.0 0.0 2:05.04 sh