My Ubuntu 10.04 LTS Profile
LINODE 1536
Running Drupal website : http://www.karmalynx.com

LAMP + Memcache



I am a LINUX NOOB - My site is clearly misconfigured some where -

It runs fine and then all of the sudden it starts swapping until you can't even terminal in. I have seen maybe 10 users on the site at a time. Here is my top:


top - 08:00:09 up 2:07, 1 user, load average: 0.14, 0.22, 0.40
Tasks: 76 total, 1 running, 75 sleeping, 0 stopped, 0 zombie
Cpu(s): 6.7%us, 2.8%sy, 0.0%ni, 90.4%id, 0.0%wa, 0.0%hi, 0.0%si, 0.1%st
Mem: 1541716k total, 1045544k used, 496172k free, 7992k buffers
Swap: 262140k total, 37348k used, 224792k free, 816504k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1943 mysql 20 0 150m 46m 2232 S 43 3.1 39:32.65 mysqld
3484 www-data 20 0 54040 26m 4828 S 12 1.8 0:03.66 apache2
3477 www-data 20 0 53984 25m 4284 S 9 1.7 0:03.12 apache2
3469 www-data 20 0 52936 24m 4312 S 8 1.7 0:08.17 apache2
1963 nobody 20 0 71612 9196 360 S 0 0.6 0:05.85 memcached
3478 www-data 20 0 52696 24m 4300 S 0 1.6 0:03.34 apache2
3485 dave 20 0 2464 1056 824 R 0 0.1 0:00.07 top
1 root 20 0 2720 520 316 S 0 0.0 0:00.60 init
2 root 20 0 0 0 0 S 0 0.0 0:00.00 kthreadd
3 root 20 0 0 0 0 S 0 0.0 0:00.16 ksoftirqd/0
4 root 20 0 0 0 0 S 0 0.0 0:03.57 kworker/0:0
5 root 20 0 0 0 0 S 0 0.0 0:00.06 kworker/u:0
6 root RT 0 0 0 0 S 0 0.0 0:00.00 migration/0
7 root RT 0 0 0 0 S 0 0.0 0:00.00 migration/1
8 root 20 0 0 0 0 S 0 0.0 0:00.30 kworker/1:0
9 root 20 0 0 0 0 S 0 0.0 0:00.15 ksoftirqd/1
10 root RT 0 0 0 0 S 0 0.0 0:00.00 migration/2


free -m
total used free shared buffers cached
Mem: 1505 1275 229 0 10 693
-/+ buffers/cache: 571 934
Swap: 255 34 221


KeepAlive set to OFF

<IfModule mpm_prefork_module>
Start Servers 1
MinSpareServers 3
MaxSpareServers 6
MaxClients 12


<IfModule mpm_worker_module>
Start Servers 1
MinSpareThreads 3
MaxSpareThreads 6
Thread Limit 20
MaxClients 12
MaxSpareThread 20
MaxClientsChild 20

_________________
twitter - @daveferrara1

Here is mySQL config: (myslqtuner suggested these)

# * Fine Tuning
#
key_buffer = 16K
sort_buffer_size = 4M
join_buffer_size = 4M
read_rnd_buffer_size = 512K
max_allowed_packet = 1M
thread_stack = 64K
thread_cache_size = 256
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover = BACKUP
max_connections = 20
tmp_table_size = 32M
max_heap_table_size = 32M
table_cache = 256
thread_concurrency = 8


THANKS- Iappreciate the help!

_________________
twitter - @daveferrara1

Before when I tran top i had spikes up to 80.0%wa and up.

I have a drupal site. prefork was very fast for me, but the swap was crashing the site with like 10 users.


So I did some poking around and was able to switch from fork to worker. Made a monster difference.

Here is my graph breakdown. I am using higher CPU. Even got an alert about it.

https://dl.dropbox.com/u/24285670/graphs.jpeg


You'll see that the i/o is still not zero, but pretty much. (i think on linux there is always a little see linuxatemyram.com )

Anyway - switching the way i did required CGI- made a quick apt get for that and made a few changes to virtual host file per a tutorial I found for another version of Linux but it was close enough to get working.

That fixed my server but my site was downloading the page when ever you clicked a link so I had to set the base URL on my Drupal 6 website (simple uncommented a line in the settings.php file and altered the example.com)

I will post new worker set up asap to help anyone else out.

If you want my terminal notes from my cgi addition hit me up- @daveferrara1

and wholla!

_________________
twitter - @daveferrara1

Are you really using old fashioned CGI, or are you using FastCGI (via mod_fcgid or mod_proxy_fcgi)? If you really are using plain CGI, using FastCGI would produce a notable reduction in CPU usage (since regular CGI requires that a fresh PHP instance be started up for every request).

Another cheap win is an object caching module like APC, the Alternative PHP Cache. When set up correctly it has zero side-effects but speeds up execution (and reduces CPU load).

Correct I added:

sudo apt-get install libapache2-mod-fcgid

_________________
twitter - @daveferrara1