FreeBSD: stressing 4.2 and Apache with ab (fwd)

L. Cranswick L.M.D.Cranswick at
Sat Dec 30 04:57:37 GMT 2000

> >   socket: "No buffer space available"
> Sounds (if I remember correctly) that you are running out of NMB
> clusters. Increase them (probably need to add the setting: options
> NMBCLUSTERS="10000") in your kernel config file, or possibly by sysctl
> (kern.ipc.nmbclusters)
> -Steven

Thanks for this, I have done an incoherant  draft page on making 
this happen at (corrections, insults, etc appreciated):
Optimising FreeBSD 4.2 UNIX and Apache for High Performance 
PC Webserving

Things are now much more robust with respect to stress testing
using ab (apachebench).

A few more silly questions (telling me to not worry about
it and get a life is an acceptable answer).

On web searching:
I cannot find anything about tuning FreeBSD with Apache though
there are Linux equivalents - what are the parameters that
should be tweaked and what are the implications - especially
if RAM might be becoming tight - will it just swap to disk?


With nmbclusters = 10000 - it now takes a lot more to drag
FreeBSD down in these tests.  (is still a 300 MHz Pentium
with 128 Meg RAM)

But when I do:
  /usr/local/apache/bin/ab -n 10000 -c 1000

I get:
  Benchmarking (be patient)...
    socket: Too many open files in system 

And the FreeBSD consol/logs reports: /kernel: file: table is full
/var/run/utmp: Too many open files in system.
no memory for rx list, etc.

Does this give suggestions on parameters to tweak 
(just increase nmbclusters more) or am
I asking too much from the system?  I would like to
get a strategy that FreeBSD/apache starts to go slow 
rather than barfs when it starts to get under
excessive load - if this is a reasonable request.  
Or at least get the max out of it before FreeBSD starts

(I should note that FreeBSD even in default mode is
majorly out-performing my SGI O2 on these benchmarks
and seems to be doing better than the computer mentioned



Lachlan M. D. Cranswick

Collaborative Computational Project No 14 (CCP14)
    for Single Crystal and Powder Diffraction
Daresbury Laboratory, Warrington, WA4 4AD U.K
Tel: +44-1925-603703  Fax: +44-1925-603124
E-mail: l.cranswick at  Ext: 3703  Room C14

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