我有一个 AWS 服务器，它安装了带有 Magento 和 PHP-FPM 的 nginx。
该服务器当前设置为按需类型（我意识到这是错误的类型）。
Type: c3.2xlarge
CPU : 8 (2.80GHz)
RAM : 16GB
Storage : 1TB
Php version : 5.3.29
Database: Mysql 5.5.42
Magento : Community Edition 1.7.0.2
我们发现该网站全天的性能普遍很差，但在某些时候，性能会变得更糟，所有 8 个核心处理器的 CPU 使用率都会达到并保持在 100%。
这是一个典型的糟糕结果：
http://www.webpagetest.org/result/151210_YE_WGT/
此时‘top’命令的输出为：
top - 16:14:39 up 23:56, 4 users, load average: 16.79, 12.53, 9.55
Tasks: 160 total, 18 running, 142 sleeping, 0 stopped, 0 zombie
Cpu(s): 95.4%us, 3.7%sy, 0.0%ni, 0.2%id, 0.0%wa, 0.0%hi, 0.6%si, 0.0%st
Mem: 15406732k total, 15262420k used, 144312k free, 1488728k buffers
Swap: 2097148k total, 5848k used, 2091300k free, 10431604k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
10529 apache 20 0 585m 97m 60m R 46.5 0.7 3:09.96 php-fpm
10494 apache 20 0 503m 88m 58m R 44.2 0.6 2:40.60 php-fpm
10562 apache 20 0 579m 75m 55m R 43.9 0.5 2:37.47 php-fpm
10566 apache 20 0 503m 88m 59m R 43.9 0.6 2:06.87 php-fpm
10570 apache 20 0 508m 95m 61m R 43.9 0.6 2:58.97 php-fpm
10541 apache 20 0 505m 82m 51m R 43.6 0.5 3:06.50 php-fpm
10549 apache 20 0 508m 90m 56m R 43.6 0.6 2:51.53 php-fpm
10552 apache 20 0 501m 83m 57m R 43.2 0.6 3:07.36 php-fpm
10577 apache 20 0 505m 87m 56m R 43.2 0.6 2:53.10 php-fpm
10576 apache 20 0 505m 76m 45m R 42.9 0.5 2:33.44 php-fpm
10559 apache 20 0 506m 90m 58m R 41.9 0.6 3:05.21 php-fpm
10554 apache 20 0 503m 91m 61m S 40.9 0.6 2:43.36 php-fpm
10572 apache 20 0 502m 82m 53m R 40.6 0.5 2:59.19 php-fpm
10567 apache 20 0 503m 79m 50m R 39.6 0.5 2:05.11 php-fpm
10553 apache 20 0 504m 84m 54m R 38.9 0.6 2:41.71 php-fpm
10535 apache 20 0 506m 91m 60m R 34.6 0.6 3:09.11 php-fpm
10571 apache 20 0 569m 85m 61m S 34.6 0.6 3:02.31 php-fpm
10516 apache 20 0 496m 82m 60m S 33.6 0.6 2:29.04 php-fpm
10573 apache 20 0 500m 85m 58m R 29.3 0.6 2:30.34 php-fpm
10546 apache 20 0 501m 80m 52m R 19.6 0.5 2:40.74 php-fpm
1536 root 20 0 1089m 743m 1848 S 1.3 4.9 11:51.52 redis-server
2722 do_ssh_a 20 0 117m 3716 2768 S 1.0 0.0 12:38.60 htop
3776 nobody 20 0 74312 11m 5392 S 1.0 0.1 0:12.81 nginx
17658 do_ssh_a 20 0 119m 5508 2768 S 1.0 0.0 6:50.49 htop
3775 nobody 20 0 74244 11m 5392 S 0.3 0.1 0:12.35 nginx
首次字节时间 (TTFB) 从“良好”网页测试结果的 4 秒飙升至 27 秒（http://www.webpagetest.org/result/151210_MV_VQ3/）。
nginx 配置先前是：
pm = static
pm.max_children = 20
我们尝试了
pm = ondemand
pm.process_idle_timeout = 10s;
但这并没有多大帮助。有什么建议可以让我进一步调查这个问题吗？
编辑1
我在 /etc/php-fpm.d/www.conf 中做了以下更改
pm = ondemand
pm.process_idle_timeout = 30s;
pm.max_requests = 50
这大大提高了加载时间。
从：
Load Time First Byte
37.847s 33.165s
(http://www.webpagetest.org/result/151211_EX_H2C/)
到：
Load Time First Byte
10.203s 5.141s
(http://www.webpagetest.org/result/151211_GX_J5N/)
编辑2
EDIT1 中提到的更改后的“top”输出
top - 11:59:21 up 1 day, 19:40, 6 users, load average: 12.79, 12.09, 12.73
Tasks: 184 total, 13 running, 170 sleeping, 0 stopped, 1 zombie
Cpu(s): 93.7%us, 3.9%sy, 0.0%ni, 1.7%id, 0.0%wa, 0.0%hi, 0.7%si, 0.0%st
Mem: 15406732k total, 15202804k used, 203928k free, 1238548k buffers
Swap: 2097148k total, 7580k used, 2089568k free, 10513760k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
6585 apache 20 0 503m 77m 47m S 64.4 0.5 0:45.25 php-fpm
6587 apache 20 0 506m 90m 58m R 52.5 0.6 0:39.24 php-fpm
6580 apache 20 0 510m 88m 52m R 51.8 0.6 0:50.26 php-fpm
6581 apache 20 0 505m 79m 47m R 50.5 0.5 0:45.86 php-fpm
6570 apache 20 0 511m 95m 58m R 49.8 0.6 0:48.71 php-fpm
6682 apache 20 0 506m 77m 44m R 49.5 0.5 0:19.54 php-fpm
6608 apache 20 0 513m 97m 57m R 48.8 0.6 0:41.21 php-fpm
6584 apache 20 0 505m 85m 54m S 48.5 0.6 0:43.91 php-fpm
6613 apache 20 0 504m 78m 47m R 48.5 0.5 0:37.55 php-fpm
6616 apache 20 0 594m 83m 48m R 47.8 0.6 0:36.26 php-fpm
6615 apache 20 0 503m 80m 51m R 41.5 0.5 0:30.82 php-fpm
6586 apache 20 0 506m 87m 55m R 34.9 0.6 0:41.42 php-fpm
6576 apache 20 0 498m 75m 50m S 33.2 0.5 0:52.00 php-fpm
6609 apache 20 0 497m 84m 61m S 28.6 0.6 0:36.51 php-fpm
6588 apache 20 0 588m 80m 51m S 26.9 0.5 0:40.33 php-fpm
6575 apache 20 0 582m 75m 52m R 20.9 0.5 0:49.75 php-fpm
6612 apache 20 0 504m 85m 55m S 20.6 0.6 0:37.31 php-fpm
6614 apache 20 0 582m 75m 52m S 20.3 0.5 0:33.36 php-fpm
6579 apache 20 0 496m 77m 54m R 19.9 0.5 0:49.18 php-fpm
6577 apache 20 0 499m 82m 57m S 19.3 0.6 0:50.45 php-fpm
21731 do_ssh_a 20 0 119m 5264 2620 S 1.7 0.0 5:44.07 htop
3800 ec2-user 20 0 117m 3340 2628 S 1.3 0.0 0:36.39 htop
6527 do_ssh_a 20 0 117m 3464 2636 S 1.3 0.0 0:03.67 htop
1536 root 20 0 1257m 738m 1820 S 1.0 4.9 21:07.51 redis-server
3079 nobody 20 0 73632 10m 5592 S 0.7 0.1 0:06.75 nginx