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From "Peter Crowther" <>
Subject [OT] RE: Tomcat Requirements?
Date Tue, 30 Nov 2004 10:42:41 GMT
[I'm marking this OT as it's looking increasingly like a database issue]

> From: Chris Cherrett [] 
> Tomcat averaged 15% CPU
> Mysql spiked the CPU usage to 100% when hit with long queries.

Bloody.  Would you expect that to be the case?  Naively, I'd be looking
at my database indexing at this point and seeing what was causing mySQL
to have problems.

> Would this be an indication of the need for RAM, or the need 
> for a faster CPU?

Without seeing some memory and disk I/O figures, I can't answer that -
simply measuring the CPU gives you one dimension of (at least) a
3-dimensional puzzle.

Intuitively, if mySQL is at 100% CPU, you don't need more RAM - it's got
all its data in RAM and is just having problems with the queries.
You're maxing out the CPU, which tells me that either you have some very
complex queries or that your indexing is sub-optimal - perhaps both!
But I'd like to see pages/sec and disk I/O figures before confirming it.

		- Peter

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