Perlbal and Last.fm

Russ Garrett russ at last.fm
Fri Jan 14 17:09:36 PST 2005


On Fri, 2005-01-14 at 15:01 -0800, Brad Fitzpatrick wrote:
> Awesome!
> 
> tarball or cvs version?
> 
> Would you mind posting your config?
> 
> I feel some latency clicking links on your site... are you using
> verify_backend?

We're using the tarball version, with pretty much the (untweaked)
example config (using verify_backend and random balancing). I might try
the CVS now. Are there any parameters that need altering from the
default?

I suspect the latency may well be because our servers are overloaded -
we've got a third web head on order, since the current two are maxed out
on CPU. We still have big problems with PHP in terms of it eating way
more CPU than it should, but we're at the point at the moment where we
can afford to throw money at the problem more than time :). Our average
page generation time is something like 1 second, and given that we use
memcached in anger, most of that is probably CPU-bound.

The overload was what prompted the change to perlbal - I wanted to see
if it would handle the load any better, which it does. Pound used a
fixed user-provided balancing ratio, which is hard to get right - turns
out the effective ratio using perlbal is 0.9:1 between our 2.8GHz and
3.06Ghz boxes...

Russ



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