[isf-wifidog] performance and cache_lite

[Gabe Sawhney]

So, our auth server is running on a machine with only 512MB RAM, but I'm
still surprised at how little it takes for it to spin out of control, and
ultimately become non-responsive (due to swap thrashing and consequential
skyrocketing load avg).

It appears that the times that the server goes crazy is when an
unauthenticated user at one of our hotspots blasts a pile of HTTP requests,
each of which get forwarded to the login page.  (The classic example is
opening an RSS reader, which aggressively tries to fetch dozens of feeds.)
But the fact that something so mundane can take out our server is
frustrating.

We weren't running Cache_Lite, so I tried installing it.  I've never tried
to understand how caching in PHP works, but setting it up wasn't as easy as
I hoped.  I installed it ("pear install Cache_Lite"), then set the relevant
value to true in config.php, and got:
Uncaught exception 'Exception' with message 'Component not found' in
/var/www/wifidog-auth/wifidog/classes/Dependency.php:467

We're using wifidog rev 1390.  Cache_Lite works fine when I test it
separately.

So, I have two questions:
1) Does wifidog require a way more powerful box than I'm trying to run it
on?  (If not, what could be causing this instability we're experiencing?)
2) What am I missing with the Cache_Lite setup?

Gabe
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