[rt-users] Performance Issues

[Dan Pritts]

On Thu, Sep 09, 2004 at 02:44:47PM -0400, Michael S. Liebman wrote:
> On Thu, Sep 09, 2004 at 02:26:33PM -0400, Dan Pritts wrote:
> > mysql is only using about 10 megs of RAM, FWIW.
> 
> That's probably not ideal. Have a look at the sample mysql
> configurations and choose which one is appropriate for your setup,
> most likely the large.

Where?  Is this something I should be looking for on the mysql
site?  I couldn't find it in the RT documentation, the RT source,
or the RT wiki.  

I'm surprised I need a "large" configuration for a database that does
not yet have 100 tickets.

> > It's not.  It has 1G of ram and does nothing beyond run processes
> > beyond what's required for RT.  It currently has 256M or so free, plus
> > 256M or so used for file cache.  
> 
> That doesn't mean its not swapping. You've forced mysql to use 10MB
> and no more of RAM. If it needs more, it will swap once it reaches
> it's limit, regardless of physical memory.

It might be paging but it's not swapping.  watching with "free" running
in a 1-second loop shows zero swap usage.  It has a 33M vsize (vs the 10M
ram usage) so you might have something here - but it should not really
be a performance problem on the level we are talking about if it is not
actually swapping.  Since the system file cache is holding everything
in ram anyway, worst case it pages in the files that are already cached.

I'm hardly a database expert, though.  I can imagine that mysql
might optimize for memory in doing its queries instead of optimizing
for speed unless told otherwise - but is this really potentially 
taking 5-10 seconds to pull up one ticket?    

This doesn't explain why the system spends all this CPU time in
mason_handler.cgi though, and I frankly find it difficult to believe
that more than 10 megs of ram is needed for reasonable DB performance
with a DB of less than 100 tickets.

I will check into InnoDB.

danno
--
dan pritts                                       danno at internet2.edu
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