[Gllug] web server performance

[Jason Clifford]

On Thu, 28 Apr 2005, Alain Williams wrote:

> Can anyone offer tips on monitoring web server performance ?
> 
> I am helping to look after a small web server (apache/php/mysql) on a small box
> (64MB bytemark - running debian). It works well most of the time, nice & fast,
> but occasionally some users report very sluggish response. It is running at
> a couple of hits a second, the database part is very light.
> 
> Looking at the apache log doesn't really help since that shows when apache sent the
> reply to the browser - it does not show how long it took between when the request
> arrived and when the reply was sent.

I suspect the problem is not anything you can manage directly as your 
server is a UML instance and they are subject to io latency - particularly 
disk io - which causes exactly the kind of thing you've indicated.

I've seen this a little here at UKFSN and it's convinced me that I need to 
check out Xen rather than UML for the vserver offerings here.

You might be able to reduce the impact of the problem with more memory. Do 
ensure that your memory allocation does not include swap from the host 
system but is based only on real memory. I believe that this is the case 
at Bytemark.

Jason Clifford
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