Hi Tony,usually httpd consumes a very little amount of memory, if it is behaving in that way it is probably due to some module like mod_php. Can you give us a bit more info about your mpm used and the list of modules loaded? For example, the most common use case that we see is mpm-prefork and mod_php causing a ton of RAM consumed (each httpd process allocates memory for a PHP interpreter), meanwhile a solution like mpm-worker|event + mod_proxy_fcgi + php-fpm works way better.My suggestion would be to narrow down what module is really causing your memory to saturate before tuning the mpm.Luca2017-09-06 1:33 GMT+02:00 Tony DiLoreto <tony@xxxxxxxxxxxxxxxxxxxxxxxx>:Hi Luca,Basically my server runs out of free memory and freezes. On AWS I have to stop/start it again to be able to SSH in. What I'd really like is a MAX_PERCENTAGE_AVAILABLE_MEMORY directive that limits Apache to <= some % of free memory. That way it can never halt my system.Hope this helps.On Tue, Sep 5, 2017 at 1:16 PM Luca Toscano <toscano.luca@xxxxxxxxx> wrote:Hi Tony,2017-08-31 23:43 GMT+02:00 Tony DiLoreto <tony@xxxxxxxxxxxxxxxxxxxxxxxx>:Hi All,I've been scouring the internet for best practices or heuristics for specifying parameter values of the MPM directives. My server seems to lock up regardless of the values I enter. Are there "rules of thumb" for each MPM type (prefork, worker, event)?Can you tell us what do you mean with "lock up"?Luca--Tony DiLoretoPresident & CEOMigliore Technologies Inc716.997.2396The best in the business...period!