我想找到 Web 服务器的瓶颈（运行在 32GB RAM/24 核上）启用 HT请参阅 Apache/mod_php）。
以下是我的观察，
- 内存似乎不是问题（只有 10MB 的交换空间）
- 提供静态内容的速度非常慢
- php 性能看起来不错（页面加载时间不到一秒）
- CPU 使用率高，有时 SYS 百分比会急剧上升（如下所示）
我猜第一步应该是在 apache 前面使用 ngnix 来提供静态内容？
或者 MPM-worker apache 和 php-fpm 作为替代方案怎么样？请提出建议并帮助我改进这个问题。
top - 11:22:54 up 170 days, 2:35, 6 users, load average: 324.55, 210.85, 105.87
Tasks: 1351 total, 353 running, 990 sleeping, 7 stopped, 1 zombie
Cpu0 : 0.9%us, 98.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 1.1%si, 0.0%st
Cpu1 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu2 : 3.7%us, 96.3%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu3 : 2.8%us, 97.2%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu4 : 3.4%us, 96.6%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu5 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu6 : 0.0%us, 99.1%sy, 0.9%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu7 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu8 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu9 : 6.6%us, 93.4%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu10 : 0.6%us, 99.4%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu11 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu12 : 6.6%us, 92.9%sy, 0.6%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu13 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu14 : 0.6%us, 99.4%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu15 : 0.3%us, 99.7%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu16 : 8.5%us, 91.5%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu17 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu18 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu19 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu20 : 6.3%us, 93.7%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu21 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu22 : 4.5%us, 95.5%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Cpu23 : 0.0%us,100.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 32869868k total, 22865280k used, 10004588k free, 177048k buffers
Swap: 4194296k total, 104016k used, 4090280k free, 3578260k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
6736 apache 20 0 371m 59m 3724 R 7.6 0.2 0:28.97 httpd
6868 apache 20 0 362m 45m 3756 R 7.6 0.1 0:23.53 httpd
384 apache 20 0 350m 39m 3692 R 7.3 0.1 0:13.44 httpd
488 apache 20 0 340m 32m 3848 R 7.3 0.1 0:15.58 httpd
508 apache 20 0 328m 22m 4156 R 7.3 0.1 0:47.30 httpd
731 apache 20 0 330m 22m 3852 R 7.3 0.1 0:42.05 httpd
1028 apache 20 0 360m 48m 4168 R 7.3 0.2 0:45.40 httpd
1113 apache 20 0 365m 58m 4168 R 7.3 0.2 0:28.10 httpd
1197 apache 20 0 340m 34m 4156 R 7.3 0.1 0:38.98 httpd
1373 apache 20 0 364m 59m 4860 R 7.3 0.2 0:36.98 httpd
[Sat Feb 22 09:40:25 2014] [notice] child pid 23674 exit signal Segmentation fault (11)
[Sat Feb 22 11:15:01 2014] [notice] child pid 24974 exit signal Segmentation fault (11)
[Sat Feb 22 11:15:03 2014] [notice] child pid 5107 exit signal Segmentation fault (11)
[Sat Feb 22 11:15:06 2014] [notice] child pid 23932 exit signal Segmentation fault (11)
[Sat Feb 22 11:15:06 2014] [notice] child pid 486 exit signal Segmentation fault (11)
[Sat Feb 22 11:15:07 2014] [notice] child pid 5269 exit signal Segmentation fault (11)
[Sat Feb 22 11:15:10 2014] [notice] child pid 2391 exit signal Segmentation fault (11)
[Sat Feb 22 11:15:10 2014] [notice] child pid 5295 exit signal Segmentation fault (11)
[Sat Feb 22 11:15:15 2014] [error] server reached MaxClients setting, consider raising the MaxClients setting
[Sat Feb 22 11:23:46 2014] [warn] child process 27887 still did not exit, sending a SIGTERM
[Sat Feb 22 11:23:46 2014] [warn] child process 5260 still did not exit, sending a SIGTERM
[Sat Feb 22 11:23:46 2014] [warn] child process 6713 still did not exit, sending a SIGTERM
[Sat Feb 22 11:23:48 2014] [warn] child process 27887 still did not exit, sending a SIGTERM
[Sat Feb 22 11:23:48 2014] [warn] child process 5260 still did not exit, sending a SIGTERM
[Sat Feb 22 11:23:48 2014] [warn] child process 6713 still did not exit, sending a SIGTERM
[Sat Feb 22 11:23:50 2014] [warn] child process 27887 still did not exit, sending a SIGTERM
[Sat Feb 22 11:23:50 2014] [warn] child process 5260 still did not exit, sending a SIGTERM
[Sat Feb 22 11:23:50 2014] [warn] child process 6713 still did not exit, sending a SIGTERM
[Sat Feb 22 11:23:52 2014] [error] child process 27887 still did not exit, sending a SIGKILL
[Sat Feb 22 11:23:52 2014] [error] child process 5260 still did not exit, sending a SIGKILL
[Sat Feb 22 11:23:52 2014] [error] child process 6713 still did not exit, sending a SIGKILL