I can go even one step further. 255 servers, 2.5 Gig of ram, huge config (200 virtuals hosts, 1500 redirect rules, 2000 rewrite rules, 300 proxy rules) and I never go into swap using prefork.
I believe 255 concurrent clients is really low now-a-days for high-end production servers. Heck, 2.x's hard limit is 200,000 not 256. (Reason #1001 why 2.x is better than 1.3.) =)
It's when you start to get into several thousand concurrent connections that I've found that the memory model of prefork starts to get painful. And memory usage also depends on whether your OS does optimistic or pessimistic memory allocation. It's impossible to run high MaxClients with prefork on, say, Solaris without having large amounts of swap dedicated. -- justin
