Update: I’ve changed my mind a bit. Mongrel should be on par with thin memory wise, as thin is based on mongrel. So I’m guessing that the gray bar is the (commercial) Litespeed setup an the green bar is nginx + mongrel
The Guys from Phusion created a patch for ruby 1.8.x that is supposed to improve the memory consumption of your webapp.
They recently launched the ruby enterprise edition website to advertise this patch. On the site there are some stats, but without labels, so you need to guess which setup performs the best in speed and memory consumption.
My guess:
The purple bar is offcourse Apache (Worker MPM) + Ruby Enterprise Edition + Passenger as it’s the one with the best performance and best memory consumption, otherwise the patch would be pointless.
The grey bar is probably Nginx with Mongrel as it’s the one with the worst memory consumption but speedy.
Now it becomes more difficult. The following four bars (blue, red, orange, green) have similar memory usage, but only the “orange setup” is considerable less speedy than the other setups. As the Apache Prefork MPM is not as performing as the Worker MPM (according to the apache docs), I would guess the orange bar stands for the Apache (prefork MPM) + Passenger configuration.
Ok, three down..three to go: blue, red, green and litespeed, apache (worker MPM) + passenger, and Nginx + thin. As there is almost no variation in memory usage and speed, i’m going to guess:
blue = thin, green = litespeed and red = apache (worker MPM) + passenger.
Let’s see if I win a original limited edition phusion t-shirt 
