Re: [tlug] Re: [RFC] Outline of the fast HTTP talk (PHP benchmark)

[Francois Cartegnie <fcartegnie@example.com>]

> I'm not clear what all this means. FastCGI from lighttpd does not issue
> multiple simultaneous requests to an FCGI server, so one generally has
> hundreds of FCGI servers runnning on a reasonably well loaded machine.
> These processes certainly are preemptible, and while the individual
> back-ends are FIFO, neither the group as a whole nor lighttpd is.
>
> I'm also not sure on what CPU affinity is being set; with this many
> processes, one would think that the automatic CPU affinity would be
> fine.

There's the cpu affinity, which sets wich process runs on which cpu (the 
dynamic you mention) but he uses the affinity tool function that changes the 
process scheduler SCHED_FIFO (realtime) for the lighttpd process. Such a 
process runs until it releases the cpu by itself, and is only interruptible 
by a process of a higher priority. (and as kmigrate is FIFO/prio 99, can 
still be migrated to another cpu on multi core systems).

So I think lighty is just doing sequencial processing of requests (as their 
process are with same prio, so all exclusive) and no more paralellism in 
processing is possible.