What is the best apache MPM for Linode 512

I'm not entirely sure exactly what you're asking, but on a Drupal site with 512mb of memory, the least amount of memory a PHP script can consume without experiencing problems is the best amount.

Unless you have are using 100 modules or uploading 1200x1200 pics for ImageCache to process, you should be okay with 48mb to 64mb.

As far as preforking, I'll let the pros step in and guide you there as I'd be lying if I spoke about the topic with any authority.

thank you very much dear nanerpuss for help

I was looking for best MPM adjustment for my server but at same time be suitable with PHP 5.2 memory_limit (I gives it 256MB) and MysqlSrv5 reserved memory(default- I don not make a count)

I suggest the following config - and still in performance testing

 <ifmodule prefork.c="">StartServers       3
MinSpareServers    3
MaxSpareServers    5
#ServerLimit      256
MaxClients        20
MaxRequestsPerChild  2000</ifmodule> 

for Drupal setting 256M for php - avoid unable to allocated (XXXX bytes ) of memory message of PHP. and yes more that 150 module :)

thanks and regards

@math:

for Drupal setting 256M for php - avoid unable to allocated (XXXX bytes ) of memory message of PHP. and yes more that 150 module :)

Well that may certainly cause some issues. I typically try and stay under 100 enabled modules myself even thought that is still very liberal. If I were making a Drupal site with a good budget and plenty of time to work, I can get by with less than 30 of the most vital modules… the rest I do myself.

Sometimes though you have to make do with what you have!