I have some questions about my web server. Its a LAMP web server running centos 5.5 and php5, mysql5. The server gets hundreds (maybe thousand) of concurrent users during peak hours.
I'm trying to optimize a little and understand "top". From what I can see:
all 16GB of my ram have been used up?
does that mean that my server needs more memory?
My swap is only 2GB, should it be increased?
usually during peak hours my server load average first number is about 2.5-3. What could I do to optimize the server so that the load average even during peak doesn't go above 1? In the past I was told a good working server should stay under 1 load, is this still true? Although even during load of 2.5-3, server pages and applications seem to load with pretty good speed.
what should the memory size in php.ini be set to?
top - 14:30:18 up 2 days, 12:41, 5 users, load average: 1.25, 1.74, 2.92
Tasks: 305 total, 2 running, 302 sleeping, 0 stopped, 1 zombie
Cpu(s): 6.3%us, 0.9%sy, 0.0%ni, 92.5%id, 0.2%wa, 0.0%hi, 0.1%si, 0.0%st
Mem: 16427200k total, 16111472k used, 315728k free, 3120316k buffers
Swap: 2104496k total, 268k used, 2104228k free, 6216756k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 29080 apache 15 0 358m 36m 5192 S 20.2 0.2 2:08.40 httpd
29093 apache 18 0 357m 36m 5192 S 18.2 0.2 2:02.52 httpd 29079 apache 15 0 370m 49m 5832 S 10.0 0.3 2:32.14 httpd
1812 apache 15 0 370m 49m 5196 S 7.3 0.3 2:25.30 httpd 5204 apache 15 0 358m 36m 5168 S 5.3 0.2 0:59.28 httpd
29075 apache 15 0 370m 48m 5184 S 3.3 0.3 2:15.93 httpd 9712 apache 15 0 360m 38m 5180 S 3.0 0.2 0:54.81 httpd
29072 apache 16 0 358m 36m 5192 S 2.7 0.2 2:24.43 httpd 6310 apache 17 0 388m 67m 5180 S 2.3 0.4 0:58.85 httpd
8674 apache 15 0 343m 21m 4980 S 2.0 0.1 0:07.91 httpd 29085 apache 15 0 371m 49m 5224 S 2.0 0.3 2:16.86 httpd
29083 apache 15 0 370m 48m 5196 S 1.7 0.3 2:10.64 httpd 5575 apache 15 0 357m 36m 5228 S 1.3 0.2 0:53.78 httpd
29066 apache 15 0 379m 59m 5860 R 1.3 0.4 2:11.93 httpd 29078 apache 15 0 370m 48m 5188 S 1.3 0.3 2:14.52 httpd
29084 apache 15 0 370m 48m 5208 S 1.0 0.3 2:02.49 httpd 29089 apache 15 0 370m 48m 5188 S 1.0 0.3 2:27.61 httpd
29082 apache 15 0 390m 68m 5188 S 0.7 0.4 2:32.48 httpd 29984 apache 15 0 358m 36m 5228 S 0.7 0.2 2:08.32 httpd
3571 root 16 0 13400 1792 848 S 0.3 0.0 2:37.89 top 4419 mysql 15 0 668m 175m 7204 S 0.3 1.1 3:32.25 mysqld
28181 root 15 0 90460 3624 2680 S 0.3 0.0 0:17.60 sshd 29091 apache 15 0 390m 69m 5196 S 0.3 0.4 2:29.99 httpd
32476 root 15 0 12900 1320 848 R 0.3 0.0 0:06.46 top 1 root 15 0 10372 680 572 S 0.0 0.0 0:02.01 init
2 root RT -5 0 0 0 S 0.0 0.0 0:00.51 migration/0 3 root 34 19 0 0 0 S 0.0 0.0 0:00.07 ksoftirqd/0
4 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/0 5 root RT -5 0 0 0 S 0.0 0.0 0:00.12 migration/1
6 root 34 19 0 0 0 S 0.0 0.0 0:00.03 ksoftirqd/1 7 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/1
8 root RT -5 0 0 0 S 0.0 0.0 0:00.06 migration/2 9 root 34 19 0 0 0 S 0.0 0.0 0:00.03 ksoftirqd/2
10 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/2 11 root RT -5 0 0 0 S 0.0 0.0 0:00.06 migration/3
12 root 34 19 0 0 0 S 0.0 0.0 0:00.04 ksoftirqd/3 13 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/3
14 root RT -5 0 0 0 S 0.0 0.0 0:01.45 migration/4 15 root 34 19 0 0 0 S 0.0 0.0 0:00.01 ksoftirqd/4
16 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/4 17 root RT -5 0 0 0 S 0.0 0.0 0:00.22 migration/5
18 root 34 19 0 0 0 S 0.0 0.0 0:00.01 ksoftirqd/5 19 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/5
20 root RT -5 0 0 0 S 0.0 0.0 0:00.15 migration/6 21 root 34 19 0 0 0 S 0.0 0.0 0:00.02 ksoftirqd/6
22 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/6 23 root RT -5 0 0 0 S 0.0 0.0 0:00.15 migration/7
24 root 34 19 0 0 0 S 0.0 0.0 0:00.01 ksoftirqd/7 25 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/7
26 root RT -5 0 0 0 S 0.0 0.0 0:00.19 migration/8 27 root 34 19 0 0 0 S 0.0 0.0 0:00.04 ksoftirqd/8
28 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/8 29 root RT -5 0 0 0 S 0.0 0.0 0:00.34 migration/9
30 root 34 19 0 0 0 S 0.0 0.0 0:00.03 ksoftirqd/9 31 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/9
32 root RT -5 0 0 0 S 0.0 0.0 0:00.16 migration/10 33 root 34 19 0 0 0 S 0.0 0.0 0:00.04 ksoftirqd/10
34 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/10 35 root RT -5 0 0 0 S 0.0 0.0 0:00.12 migration/11
36 root 34 19 0 0 0 S 0.0 0.0 0:00.05 ksoftirqd/11 37 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/11
38 root RT -5 0 0 0 S 0.0 0.0 0:00.35 migration/12
And here is another top paste, but its not peak time for traffic yet. Isn't it a problem that httpd is using 100% CPU?
top - 16:35:57 up 2 days, 14:47, 4 users, load average: 4.34, 3.60, 3.09
Tasks: 321 total, 3 running, 317 sleeping, 0 stopped, 1 zombie
Cpu(s): 15.0%us, 1.1%sy, 0.0%ni, 65.7%id, 18.1%wa, 0.0%hi, 0.1%si, 0.0%st
Mem: 16427200k total, 16235036k used, 192164k free, 3129048k buffers
Swap: 2104496k total, 268k used, 2104228k free, 6184496k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
540 apache 25 0 385m 63m 4720 R 100.1 0.4 0:22.11 httpd
16194 apache 18 0 358m 36m 5188 S 29.6 0.2 2:42.62 httpd
1759 apache 15 0 391m 69m 5188 S 20.6 0.4 3:32.70 httpd
1761 apache 17 0 388m 67m 5844 S 20.0 0.4 3:32.70 httpd
5420 apache 16 0 357m 36m 5816 S 18.0 0.2 3:29.58 httpd
1758 apache 16 0 358m 37m 5188 S 15.3 0.2 3:11.11 httpd
26922 apache 16 0 366m 45m 4148 R 12.6 0.3 0:29.59 httpd
13655 apache 15 0 371m 49m 5840 S 6.3 0.3 5:22.93 httpd
26894 apache 15 0 358m 36m 5124 S 6.0 0.2 1:00.43 httpd
26925 apache 15 0 358m 36m 5156 S 2.0 0.2 0:29.61 httpd
13654 apache 15 0 358m 36m 5200 S 1.3 0.2 5:06.32 httpd
23337 apache 15 0 359m 37m 5184 S 1.3 0.2 3:02.68 httpd
24108 apache 16 0 357m 35m 5180 S 1.3 0.2 0:48.09 httpd
28473 apache 15 0 357m 35m 5128 S 1.3 0.2 0:25.66 httpd
584 apache 15 0 357m 35m 5068 S 1.0 0.2 0:12.12 httpd
2687 apache 15 0 370m 48m 5168 S 1.0 0.3 3:26.85 httpd
26893 apache 15 0 357m 35m 5144 S 1.0 0.2 0:33.74 httpd
26923 apache 15 0 357m 35m 5072 S 1.0 0.2 0:33.96 httpd
26924 apache 15 0 360m 38m 5156 S 1.0 0.2 0:58.06 httpd
585 apache 15 0 357m 35m 5096 S 0.7 0.2 0:11.08 httpd
17329 apache 15 0 369m 48m 5176 S 0.7 0.3 1:15.52 httpd
1760 apache 15 0 389m 68m 5856 D 0.3 0.4 3:36.45 httpd
4419 mysql 15 0 668m 175m 7204 S 0.3 1.1 4:04.57 mysqld
1 root 15 0 10372 680 572 S 0.0 0.0 0:02.04 init
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