PHP-FPM opinion needed: 1 pool for all, or 1 pool per site?
I'm trying to find out what would be more efficient memory wise. Using one PHP-FPM pool for all the websites on the server, or to use a pool per site.
Here is my experience so far...
The first logical thing that came up to my mind, is to use a "pool per site" structure. Because it makes more sense... I tried it on OpenVz. But then I ran out of memory pretty fast. It was before I figured out about the "ulimit -s" thing in OpenVz: http://www.lowendbox.com/blog/reduce-stack-limit-for-multi-thread-apps/
Anyway... I installed my next VPS using only one pool, under "www-data" user. It works fine, however I noticed that the PHP-FPM processes take 2X times more memory in that setup. However, it may be due to having more traffic as well...
The specs for both servers are OpenVz 512Ram with 4 cores.
On which circumstances would you use one-pool-for-all? And when would you use one-pool-per-site?