Apache/php-fpm questions

["Rose, John B" <jbrose@xxxxxxx>]

We are experimenting with "event" MPM and PHP-FPM and comparing with "prefork" and mod_php config.

We have 48 gb RAM and 16 cores running Apache 2.4.6 on Red Hat 7, MaxRequestWorkers 2048 for "prefork" (we aren't sure what is the equiv in "event" so we just left it the default.)

ab –n 200000 –c 400 http://website.com

So the "event" config settings we use is what is here …

http://svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/extra/httpd-mpm.conf.in

We have run some tests of Directives  and combining the cpu impact of event/PHP-FPM. It seems to be noticeably higher than the result from the same test load for prefork/mod_php. 

Should the cumulative cpu/ram impact not be lower? Maybe even significantly lower?

Incidentally, when we look at "server-info" while we see …

MPM Name: event

MPM Information: Max Daemons: 11 Threaded: yes Forked: yes

We do not see any actual values for "MaxRequestWorkers", etc. listed in the output. 

Should there not be values shown for each of the settings below in the "server-info" output? 

<IfModule mpm_event_module>
    StartServers             3
    MinSpareThreads         75
    MaxSpareThreads        250
    ThreadsPerChild         25
    MaxRequestWorkers      400
    MaxConnectionsPerChild   0
</IfModule>

Is there some sort of guide to help you set the values in the "event" .conf section above, given you know your hardware resources and expected web traffic load?

Looking at the httpd-mpm.conf example page and http://httpd.apache.org/docs/2.4/mod/event.html we are not seeing a process for determining the various Directive settings.

We do not see "ServerLimit" mentioned at all in the httpd-mpm.conf example. But this, http://httpd.apache.org/docs/2.4/mod/mpm_common.html#maxrequestworkers, seems to indicate it should be there. For both "prefork" and "event". 

Is "ServerLimit" not needed at all anymore?

Thanks