性能工具之stress工具使用教程（带源码说明）

stress是一个在linux下的压力测试小工具。

我看到有些人用这个工具来描述一些资源耗尽的场景，也有人用它来做混沌测试中。请使用者要注意，这个工具并不是模拟业务问题的，是模拟系统级问题的。所以用它来模拟的时候，和业务真实场景差别还是很大的。

因为在性能工作中，经常有人因为不理解工具而误用工具，所以这里我把这个工具拿出来说明一下。

安装stress

yum install -y stress

stress参数

[root@7DGroupT1 ~]# stress
`stress' imposes certain types of compute stress on your system

Usage: stress [OPTION [ARG]] ...
 -?, --help         show this help statement
     --version      show version statement
 -v, --verbose      be verbose
 -q, --quiet        be quiet
 -n, --dry-run      show what would have been done
 -t, --timeout N    timeout after N seconds
     --backoff N    wait factor of N microseconds before work starts
 -c, --cpu N        spawn N workers spinning on sqrt()
 -i, --io N         spawn N workers spinning on sync()
 -m, --vm N         spawn N workers spinning on malloc()/free()
     --vm-bytes B   malloc B bytes per vm worker (default is 256MB)
     --vm-stride B  touch a byte every B bytes (default is 4096)
     --vm-hang N    sleep N secs before free (default none, 0 is inf)
     --vm-keep      redirty memory instead of freeing and reallocating
 -d, --hdd N        spawn N workers spinning on write()/unlink()
     --hdd-bytes B  write B bytes per hdd worker (default is 1GB)

Example: stress --cpu 8 --io 4 --vm 2 --vm-bytes 128M --timeout 10s

Note: Numbers may be suffixed with s,m,h,d,y (time) or B,K,M,G (size).

参数可以说非常简单了。大概看一眼就可以知道，它可以模拟 CPU、IO、内存、磁盘这些常见又重要的资源消耗。
下面就一一来看一下。

模拟CPU

[root@7DGroupT1 ~]# stress -c 4 -t 100

top - 10:48:11 up 63 days, 23:57,  2 users,  load average: 0.67, 1.41, 4.21
Tasks: 122 total,   5 running, 117 sleeping,   0 stopped,   0 zombie
%Cpu0  : 99.7 us,  0.3 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  :100.0 us,  0.0 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu2  :100.0 us,  0.0 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu3  :100.0 us,  0.0 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  8010528 total,  5550792 free,  1866688 used,   593048 buff/cache
KiB Swap:        0 total,        0 free,        0 used.  5762564 avail Mem

模拟 CPU 的参数很简洁。打印一下栈看一下：

[root@s6 ~]# pstack 29253
#0  0x00007f123634761b in random () from /usr/lib64/libc.so.6
#1  0x00007f1236347b39 in rand () from /usr/lib64/libc.so.6
#2  0x0000557e9ea32dbd in hogcpu ()
#3  0x0000557e9ea3180a in main ()
[root@s6 ~]

其实代码很简单，就是一个 hogcpu 函数。源码是这样的：

int
hogcpu (void)
{
  while (1)
    sqrt (rand ());

  return 0;
}

是不是看了之后觉得自己都能写一个了？不就是一个 while 吗？

模拟内存

[root@7DGroupT1 ~]# stress --vm 30 --vm-bytes 1G --vm-hang 50 --timeout 50s

[root@7DGroupT1 ~]# vmstat 1
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0      0 5606796   6828 534736    0    0  4548   212  457  710  0  0 99  1  0
 0  0      0 5597852   6976 544360    0    0  9712    52  666 1163  0  0 99  1  0
 0  0      0 5595060   7136 545828    0    0  1752     0  440  580  0  0 98  2  0
30  0      0 2125872   7136 546040    0    0     8     0 1098  522  0 21 79  0  0
 0 14      0 100896    200 211224    0    0 529748  2932 25058 43164  1 51  4 44  0
 [root@7DGroupT1 ~]# sar -B 1
 Linux 3.10.0-514.21.1.el7.x86_64 (7DGroupT1) 	10/03/2019 	_x86_64_	(4 CPU)

 10:52:49 AM  pgpgin/s pgpgout/s   fault/s  majflt/s  pgfree/s pgscank/s pgscand/s pgsteal/s    %vmeff
 10:52:50 AM      8.00     68.00    122.00      0.00   1143.00      0.00      0.00      0.00      0.00
 10:52:51 AM      0.00      0.00     29.00      0.00     25.00      0.00      0.00      0.00      0.00
 10:52:52 AM      0.00      0.00    184.00      0.00     45.00      0.00      0.00      0.00      0.00
 10:52:53 AM      0.00      0.00   2482.00      0.00    804.00      0.00      0.00      0.00      0.00
 10:52:54 AM    870.77   2436.92 172704.62      2.31  92710.00  38558.46  26820.00  61888.46     94.66
 10:52:56 AM  76853.61    618.56  34391.24     82.47 1297422.16 205238.14 404672.68  14717.53      2.41
 10:52:57 AM 125560.00    300.00   4875.00    110.00   5040.00      0.00      0.00      0.00      0.00
 10:52:58 AM 111080.00      0.00   8940.00     68.00   4723.00      0.00      0.00      0.00      0.00
 10:52:59 AM  80944.00      0.00   5725.00     40.00   1636.00      0.00      0.00      0.00      0.00
 10:53:00 AM  26224.00    300.00  37293.00      2.00    534.00      0.00      0.00      0.00      0.00
 10:53:01 AM   7344.00    180.00   1092.00      0.00  17475.00      0.00      0.00      0.00      0.00
 10:53:02 AM  24576.00    224.00   5725.00     41.00   1866.00      0.00      0.00      0.00      0.00
 [root@7DGroupT1 ~]# sar -r 1
 Linux 3.10.0-514.21.1.el7.x86_64 (7DGroupT1) 	10/03/2019 	_x86_64_	(4 CPU)

 10:56:55 AM kbmemfree kbmemused  %memused kbbuffers  kbcached  kbcommit   %commit  kbactive   kbinact   kbdirty
 10:57:13 AM   5582520   2428008     30.31      7648    447240   5643636     70.45   1780508    443288      3400
10:57:14 AM    101544   7908984     98.73      6736    375896  37108100    463.24   7328268    367028      3404

从上面的数据来看，确实产生了很大的 page faults，这也是模拟内存消耗的过程中必然会出现的现象。之前我也强调过，看内存够不够，就是要看这个 faluts。
在 Stress 中，怎么模拟的内存呢。来看一下。

int hogvm (long long bytes, long long stride, long long hang, int keep)
{
  long long i;
  char *ptr = 0;
  char c;
  int do_malloc = 1;

  while (1)
    {
      if (do_malloc)
        {
          dbg (stdout, "allocating %lli bytes ...\n", bytes);
          if (!(ptr = (char *) malloc (bytes * sizeof (char))))
            {
              err (stderr, "hogvm malloc failed: %s\n", strerror (errno));
              return 1;
            }
          if (keep)
            do_malloc = 0;
        }

      dbg (stdout, "touching bytes in strides of %lli bytes ...\n", stride);
      for (i = 0; i < bytes; i += stride)
        ptr[i] = 'Z';           /* Ensure that COW happens.  */

      if (hang == 0)
        {
          dbg (stdout, "sleeping forever with allocated memory\n");
          while (1)
            sleep (1024);
        }
      else if (hang > 0)
        {
          dbg (stdout, "sleeping for %llis with allocated memory\n", hang);
          sleep (hang);
        }

      for (i = 0; i < bytes; i += stride)
        {
          c = ptr[i];
          if (c != 'Z')
            {
              err (stderr, "memory corruption at: %p\n", ptr + i);
              return 1;
            }
        }

      if (do_malloc)
        {
          free (ptr);
          dbg (stdout, "freed %lli bytes\n", bytes);
        }
    }

  return 0;
}

就是一个死循环加上一个内存 malloc。

模拟磁盘

[root@7DGroupT1 ~]# stress --hdd 5 --hdd-bytes 1G

[root@7DGroupT1 ~]# top
top - 10:35:15 up 63 days, 23:44,  2 users,  load average: 9.14, 8.49, 8.29
Tasks: 124 total,   2 running, 122 sleeping,   0 stopped,   0 zombie
%Cpu0  :  0.0 us,  5.8 sy,  0.0 ni,  0.0 id, 94.2 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  :  1.0 us,  1.0 sy,  0.0 ni, 14.4 id, 83.6 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu2  :  0.0 us,  4.4 sy,  0.0 ni,  0.0 id, 95.6 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu3  :  0.0 us,  4.1 sy,  0.0 ni,  0.0 id, 95.9 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  8010528 total,  1940088 free,  1891792 used,  4178648 buff/cache
KiB Swap:        0 total,        0 free,        0 used.  5687416 avail Mem

[root@7DGroupT1 ~]# vmstat 1
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  7      0 1474132 146392 4499176    0    0     0    12    0    1  0  0 100  0  0
 0  7      0 1384720 146392 4589204    0    0     0 107624  815  966  0  3  8 88  0
 0  7      0 1292432 146392 4681232    0    0     0 98920 1036  987  0  3 13 84  0
 0  7      0 1194932 146392 4777968    0    0     0 115344 1033 1207  0  4  0 96  0
 1  6      0 1094312 146392 4880044    0    0     0 105260  928  930  0  3  5 92  0
 1  6      0 998756 146416 4974944    0    0     0 102812  862  928  0  3  0 97  0
 0  7      0 897960 146448 5075492    0    0     0 131200 1268 1565  1  4  5 91  0
 3  4      0 1626628 146472 4347076    0    0     0 82804 1444 1206  0  8 10 81  0
 0  7      0 2354208 146656 3620344    0    0     0 118112 2229 1256  0 27  2 70  0
 0  7      0 3264136 146804 2709776    0    0     0 110632 1761 1506  0  9  0 90  0
 0  7      0 3143120 146940 2831728    0    0     4 106896 1211 1112  0  5  0 95  0
 0  7      0 2961456 146940 3016064    0    0     0 91456 1484 1298  0  6  0 94  0
^C
[root@7DGroupT1 ~]# sar -d 1
10:54:19 AM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
10:54:20 AM  dev253-0    307.00     24.00 229976.00    749.19    126.47    454.24      3.26    100.00
10:54:20 AM   dev11-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00

10:54:20 AM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
10:54:21 AM  dev253-0    369.00     48.00 228528.00    619.45    127.11    347.24      2.71    100.00
10:54:21 AM   dev11-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00

10:54:21 AM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
10:54:22 AM  dev253-0    274.00     24.00 203760.00    743.74    127.45    404.61      3.65    100.00
10:54:22 AM   dev11-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00

10:54:22 AM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
10:54:23 AM  dev253-0    262.00      0.00 202000.00    770.99    127.61    486.35      3.82    100.10
10:54:23 AM   dev11-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00

10:54:23 AM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
10:54:24 AM  dev253-0    288.00      0.00 232352.00    806.78    127.92    479.62      3.47    100.00
10:54:24 AM   dev11-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
[root@7DGroupT1 ~]# iostat -x -d 1

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
vda               0.00  8603.00    4.00  255.00    16.00 101840.00   786.53   125.75  471.71    3.00  479.06   3.86 100.00
scd0              0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
vda               0.00  8952.00    4.00  294.00    16.00 117176.00   786.52   127.03  470.79    3.75  477.14   3.36 100.00
scd0              0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
vda               0.00  9059.00    1.00  266.00     4.00 101900.00   763.33   126.55  433.52    0.00  435.15   3.75 100.00
scd0              0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
vda               0.00  6234.00    0.00  273.00     0.00 96784.00   709.04   127.94  391.18    0.00  391.18   3.67 100.10
scd0              0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
[root@7DGroupT1 ~]# iotop
Total DISK READ :	0.00 B/s | Total DISK WRITE :	  102.23 M/s
Actual DISK READ:	0.00 B/s | Actual DISK WRITE:      75.93 M/s
  TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND
 8681 be/4 root        0.00 B/s   20.93 M/s  0.00 % 98.97 % stress --hdd 5 --hdd-bytes 1G
 8677 be/4 root        0.00 B/s   20.23 M/s  0.00 % 95.92 % stress --hdd 5 --hdd-bytes 1G
 8680 be/4 root        0.00 B/s   20.23 M/s  0.00 % 95.59 % stress --hdd 5 --hdd-bytes 1G
 8679 be/4 root        0.00 B/s   20.61 M/s  0.00 % 95.17 % stress --hdd 5 --hdd-bytes 1G
 8678 be/4 root        0.00 B/s   20.23 M/s  0.00 % 95.16 % stress --hdd 5 --hdd-bytes 1G
 7298 be/4 root        0.00 B/s    0.00 B/s  0.00 % 86.91 % [kworker/u8:1]
  285 be/3 root        0.00 B/s    0.00 B/s  0.00 % 86.72 % [jbd2/vda1-8]
16384 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % YDService
    1 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % systemd --syst~deserialize 21
    2 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kthreadd]
    3 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [ksoftirqd/0]
  516 be/4 libstora    0.00 B/s    0.00 B/s  0.00 %  0.00 % lsmd -d
    5 be/0 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kworker/0:0H]
  518 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % acpid
    7 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [migration/0]
    8 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcu_bh]
    9 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [rcu_sched]
   10 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [watchdog/0]
   11 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [watchdog/1]
   12 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [migration/1]
   13 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [ksoftirqd/1]
  526 be/4 polkitd     0.00 B/s    0.00 B/s  0.00 %  0.00 % polkitd --no-d~ Sour~ Thread]
   15 be/0 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kworker/1:0H]
   16 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [watchdog/2]
   17 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [migration/2]
   18 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [ksoftirqd/2]
  515 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % python -Es /us~in/tuned -l -P
   20 be/0 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kworker/2:0H]
   21 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [watchdog/3]
   22 rt/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [migration/3]
   23 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [ksoftirqd/3]
   25 be/0 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kworker/3:0H]
   27 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kdevtmpfs]
   28 be/0 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [netns]
   29 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [khungtaskd]
   30 be/0 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [writeback]

模拟磁盘，看起来效果也是非常不错的哦。来翻一下源码。

int hoghdd (long long bytes)
{
  long long i, j;
  int fd;
  int chunk = (1024 * 1024) - 1;        /* Minimize slow writing.  */
  char buff[chunk];

  /* Initialize buffer with some random ASCII data.  */
  dbg (stdout, "seeding %d byte buffer with random data\n", chunk);
  for (i = 0; i < chunk - 1; i++)
    {
      j = rand ();
      j = (j < 0) ? -j : j;
      j %= 95;
      j += 32;
      buff[i] = j;
    }
  buff[i] = '\n';

  while (1)
    {
      char name[] = "./stress.XXXXXX";

      if ((fd = mkstemp (name)) == -1)
        {
          err (stderr, "mkstemp failed: %s\n", strerror (errno));
          return 1;
        }

      dbg (stdout, "opened %s for writing %lli bytes\n", name, bytes);

      dbg (stdout, "unlinking %s\n", name);
      if (unlink (name) == -1)
        {
          err (stderr, "unlink of %s failed: %s\n", name, strerror (errno));
          return 1;
        }

      dbg (stdout, "fast writing to %s\n", name);
      for (j = 0; bytes == 0 || j + chunk < bytes; j += chunk)
        {
          if (write (fd, buff, chunk) == -1)
            {
              err (stderr, "write failed: %s\n", strerror (errno));
              return 1;
            }
        }

      dbg (stdout, "slow writing to %s\n", name);
      for (; bytes == 0 || j < bytes - 1; j++)
        {
          if (write (fd, &buff[j % chunk], 1) == -1)
            {
              err (stderr, "write failed: %s\n", strerror (errno));
              return 1;
            }
        }
      if (write (fd, "\n", 1) == -1)
        {
          err (stderr, "write failed: %s\n", strerror (errno));
          return 1;
        }
      ++j;

      dbg (stdout, "closing %s after %lli bytes\n", name, j);
      close (fd);
    }

  return 0;
}

死循环加上 for 循环不断的调用 write。这个调用，就是不停地做写的动作。这个和我们在上面看到的监控数据也是一致的。

总结

总结一下，通过这些源码说明，请你在使用的时候，要注意一下，像这样的工具，如果说只是为了单纯地消耗系统级的资源，然后观察应用在较少的可用资源下的表现如何，这样的工具是可以用的。

但是如果是想要模拟你的业务层出现的问题，那我劝你还是别用这样的工具了。