1.查看系统CPU使用
[root@web ~]# uptime 23:13:13 up 4 min, 2 users, load average: 0.00, 0.03, 0.00
发现使用率不是太高，排除程序占用CPU。
2.查看内存占用
[root@web ~]# free -m total used free shared buffers cached Mem: 384 331 52 0 0 0 -/+ buffers/cache: 331 52 Swap: 0 0 0
我的VPS是Guaranteed RAM 192MB，Burstable RAM 384MB。目前来看内存已经消耗殆尽了。
PS：写这段话期间VPS已经无法分配内存了，由于是采用VPS 基于OpenVZ，且没有虚拟内存，所以基本上内存不足的时候VPS不会崩溃，已经运行的程序可以接着运行，只不过是不是的内存分配不足罢了。
[root@web ~]# top
-bash: fork: Cannot allocate memory
3.查看各进程的内存占用，就是上面那条，重启VPS之后接着来
top - 23:25:33 up 4 min, 1 user, load average: 0.00, 0.00, 0.00 Tasks: 24 total, 1 running, 23 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 393216k total, 348112k used, 45104k free, 0k buffers Swap: 0k total, 0k used, 0k free, 0k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1 root 15 0 10364 740 620 S 0.0 0.2 0:00.19 init 1122 root 19 -4 12632 684 360 S 0.0 0.2 0:00.00 udevd 1381 root 15 0 5924 628 504 S 0.0 0.2 0:00.00 syslogd 1397 root 18 0 62644 1224 656 S 0.0 0.3 0:00.00 sshd 1406 root 22 0 21660 924 708 S 0.0 0.2 0:00.00 xinetd 1443 root 18 0 12076 1492 1192 S 0.0 0.4 0:00.03 mysqld_safe 1976 mysql 15 0 316m 35m 6296 S 0.0 9.2 0:00.13 mysqld 2024 root 15 0 62836 2068 680 S 0.0 0.5 0:00.00 sendmail 2032 smmsp 21 0 58344 1776 628 S 0.0 0.5 0:00.00 sendmail 2041 root 18 0 248m 6080 1124 S 0.0 1.5 0:00.00 php-fpm 2042 nginx 15 0 262m 38m 18m S 0.0 10.1 0:00.62 php-fpm 2043 nginx 15 0 250m 25m 17m S 0.0 6.5 0:00.15 php-fpm 2044 nginx 16 0 250m 25m 17m S 0.0 6.5 0:00.13 php-fpm 2046 nginx 15 0 250m 25m 17m S 0.0 6.5 0:00.13 php-fpm 2047 nginx 15 0 250m 25m 17m S 0.0 6.5 0:00.14 php-fpm 3078 root 17 0 43324 1088 300 S 0.0 0.3 0:00.00 nginx 3079 nginx 15 0 43792 1976 788 S 0.0 0.5 0:00.00 nginx 3080 nginx 18 0 43792 1668 480 S 0.0 0.4 0:00.00 nginx 3088 root 18 0 20884 1164 584 S 0.0 0.3 0:00.00 crond 3096 root 18 0 46756 824 424 S 0.0 0.2 0:00.00 saslauthd 3097 root 18 0 46756 556 156 S 0.0 0.1 0:00.00 saslauthd 3103 root 18 0 85936 3340 2620 S 0.0 0.8 0:00.02 sshd 3107 root 18 0 12080 1724 1300 S 0.0 0.4 0:00.01 bash 3135 root 18 0 12624 1196 936 R 0.0 0.3 0:00.00 top
输入M按内存使用排序
top - 23:26:47 up 5 min, 1 user, load average: 0.06, 0.03, 0.00 Tasks: 24 total, 1 running, 23 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 393216k total, 349340k used, 43876k free, 0k buffers Swap: 0k total, 0k used, 0k free, 0k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2042 nginx 15 0 262m 38m 18m S 0.0 10.1 0:00.62 php-fpm 1976 mysql 15 0 316m 35m 6296 S 0.0 9.2 0:00.14 mysqld 2043 nginx 15 0 250m 25m 17m S 0.0 6.6 0:00.32 php-fpm 2044 nginx 15 0 250m 25m 17m S 0.0 6.6 0:00.26 php-fpm 2046 nginx 15 0 250m 25m 17m S 0.0 6.5 0:00.13 php-fpm 2047 nginx 15 0 250m 25m 17m S 0.0 6.5 0:00.14 php-fpm 2041 root 18 0 248m 6080 1124 S 0.0 1.5 0:00.00 php-fpm 3103 root 18 0 86080 3352 2620 S 0.0 0.9 0:00.03 sshd 2024 root 18 0 62836 2068 680 S 0.0 0.5 0:00.00 sendmail 3079 nginx 15 0 43792 1976 788 S 0.0 0.5 0:00.00 nginx 2032 smmsp 21 0 58344 1776 628 S 0.0 0.5 0:00.00 sendmail 3107 root 18 0 12080 1724 1300 S 0.0 0.4 0:00.01 bash 3080 nginx 18 0 43792 1668 480 S 0.0 0.4 0:00.00 nginx 1443 root 18 0 12076 1492 1192 S 0.0 0.4 0:00.03 mysqld_safe 1397 root 18 0 62644 1224 656 S 0.0 0.3 0:00.00 sshd 3135 root 15 0 12624 1200 940 R 0.0 0.3 0:00.02 top 3088 root 18 0 20884 1164 584 S 0.0 0.3 0:00.00 crond 3078 root 17 0 43324 1088 300 S 0.0 0.3 0:00.00 nginx 1406 root 22 0 21660 924 708 S 0.0 0.2 0:00.00 xinetd 3096 root 18 0 46756 824 424 S 0.0 0.2 0:00.00 saslauthd 1 root 15 0 10364 740 620 S 0.0 0.2 0:00.19 init 1122 root 19 -4 12632 684 360 S 0.0 0.2 0:00.00 udevd 1381 root 15 0 5924 628 504 S 0.0 0.2 0:00.00 syslogd 3097 root 18 0 46756 556 156 S 0.0 0.1 0:00.00 saslauthd
注：PID进程ID,USER用户，PR优先级，NI(NICE)值越大实时性越高，VIRT虚拟内存，RES物理内存，SHR共享内存
看出是php-fpm与mysqld2位大仙在做怪。
找出php-fpm的配置，发现有几个值设的有点高，我打算降低一下看看结果。后来发现改善不大。
从Mysql找突破口，http://blog.s135.com/post/375/ 这里有一篇极具参考价值的文章，so按照其建议关闭InnoDB引擎，果然大有提升。
PS：关闭InnoDB引擎前应该把之前使用了该引擎的数据库转换为MYISAM,可以使用如下SQL语句：
ALTER TABLE `tablename` ENGINE = MYISAM
附上我的Mysql配置
[mysqld] ## General datadir = /var/lib/mysql tmpdir = /var/lib/mysqltmp socket = /var/lib/mysql/mysql.sock skip-name-resolve sql-mode = NO_ENGINE_SUBSTITUTION #event-scheduler = 1 ## Cache thread-cache-size = 16 table-open-cache = 4096 table-definition-cache = 2048 query-cache-size = 0M query-cache-limit = 2M ## Per-thread Buffers sort-buffer-size = 128K read-buffer-size = 1M read-rnd-buffer-size = 2M join-buffer-size = 128K ## Temp Tables tmp-table-size = 512k max-heap-table-size = 32M ## Networking back-log = 100 #max-connections = 200 max-connect-errors = 10000 max-allowed-packet = 8M interactive-timeout = 3600 wait-timeout = 600 ### Storage Engines default-storage-engine = MyISAM #innodb = FORCE skip-innodb ## MyISAM key-buffer-size = 4M myisam-sort-buffer-size = 4M # InnoDB innodb-buffer-pool-size = 8M innodb-log-file-size = 50M innodb-log-buffer-size = 8M innodb-file-per-table = 1 innodb-open-files = 300 ## Replication server-id = 1 #log-bin = /var/log/mysql/bin-log #relay-log = /var/log/mysql/relay-log relay-log-space-limit = 16G expire-logs-days = 7 #read-only = 1 #sync-binlog = 1 #log-slave-updates = 1 #binlog-format = STATEMENT #auto-increment-offset = 1 #auto-increment-increment = 2 ## Logging #log-output = FILE #slow-query-log = 1 #slow-query-log-file = /var/log/mysql/slow-log #log-slow-slave-statements long-query-time = 1 [mysqld_safe] log-error = /var/log/mysqld.log open-files-limit = 600 [mysql] no-auto-rehash
收工~