Linode 512 - MPM Prefork - WordPress hosting optimization

Edit the prefork section of the config and change MaxClients to 15 or 20, and then disable KeepAlives, restart apache. Start there.

-Chris

Thanks for those.

Any other optimation settings I should know of?

What are the optimum settings for the mpm prefork module?

StartServers 5

MinSpareServers 5

MaxSpareServers 20

ServerLimit 75

MaxClients 75

MaxRequestsPerChild 1000

Ok. I have applied the MaxClients of 20 and I am still getting the Out of Memory errors

Make it less then, if you have 8 PHP processes using 64MB of RAM then you're using your full 512MB, this isn't unusual with wordpress, keep lowering your MaxClients until the memory errors stop.

Where does the number 8 come from?

Just a random number, 8 PHP processes = 8 concurrent PHP pages being served.

Gotcha! I didn't know if that number came from the prefork settings or not. Please forgive me, I am new to Apache…

If you have many php pages. use this setting:

StartServers 5

MinSpareServers 5

MaxSpareServers 10

ServerLimit 75

MaxClients 75

MaxRequestsPerChild 1000

if your system used swap more then 300MB always, change MaxRequestsPerChild to 500.

MaxClients of 75 is a recipe for OOM. Reducing MaxRequestsPerChild only means a process will exit sooner, but Apache will still launch more processes than can fit into memory. If each Apache process is using 12M of RAM that's 900 MB on a 512 system.

Start by changing MaxClients to 10 or 20, disable KeepAlives, and move on from there.

-Chris

You should consider nginx w/ http://wordpress.org/extend/plugins/nginx-helper/

Remove w3-cache and just use the nginx helper following http://rtcamp.com/tutorials/wordpress-n … nditional/">http://rtcamp.com/tutorials/wordpress-nginx-fastcgi-cache-purge-conditional/

You may find it will considerably increase your concurrent users as it will skip php completely and serve a static html file bypassing php-fpm, except for logged in users and posting comments.