Update 23 Dec
Please see my new post here.
Managed to go through 6100rq/s by playing with Keepalive requests between backends. Seems even 1 rq/s more from apache can mean up to 200+rq/s at varnish frontend.
I’ll write a real paper on this during the next week. Meanwhile, first handmade schema explains it all. Virtous circle.
Oh, and teaser:
APC Opcode Cache is slower than on-disk static files served by Nginx. More than 3 times slower than on-disk files on a poor 80 I/Ops SATA Hard-drive.