mod_perl reqs/s @ concurrency-- for actual db based applications

[Jonathan Vanasco <suppressed>]

after talking with some people off list, I've got a question about  
performance under mod perl, for actual applications

mp shows amazing performance marks with hello world, but  few of us  
need to serve 1100 'hello worlds'

personally, i'm seeing this:

	processor: p4 2.4
	os: freebsd 6
	modperl: 2
	apache mpm: pre-fork
	
	with 2 children running, I'm handling ~70 r/s @ concurrency 10-1000
	4-8 children seems to be my point for diminishing marginal utility-  
in that range, I'm handling ~100 r/s @ concurrency 10-1000 ; and the  
numbers don't really change no matter how many servers I toss at it.

granted, i'm also benching with ab, which is old and not very  
reliable.  ( i tried to use it, but  tsung won't compile nicely on  
any of my boxes. )

i'm fairly confident that a LARGE limiting factor is db interaction  
and (b)locking. And i know that the bulk of the request timing is  
taken up in the DB or the DB/App ineraction layer.   I wouldn't be  
surprised if I those numbers double , triple , and more with a nicely  
clustered db structure.

some people I've spoken to have gotten much higher, others are   
getting much lower- which makes me feel pretty good about my  
performance tuning.

i'm just wondering what a target range for DB/Templated apps with  
moderate page logic should be ( "hello world" < Moderate Logic <  
"comprehensive statistical analysis" )