[Jax.PM] MySQL ?

[Aaron Johnson]

On Thu, 2002-10-17 at 11:43, Steve Lane wrote:
> [a jax.PM member posting]
> "William C (Bill) Jones" wrote:
> > 
> > >> What values would you give
> > >>
> > >> KEY_BUFFER=???
> > >> TABLE_CACHE=???
> > >> JOIN_BUFFER=???
> > >> RECORD_BUFFER=???
> > >> SORT_BUFFER=???
> > >> MAX_CONNECTIONS=300
> > >> TMP_TABLE_SIZE=???
> > >>
> > >> Knowing you have 6GB RAM 6GB Swap and want to handle 300 connections and be
> > >> very very fast (heck, I got 4 CPUs dedicated to this :/  :)
> > >
> > > just from experience, you'll probably gain more performance
> > > by concentrating on your table design, and how to handle
> > > expensive queries, and table locking, than from the variables.
> > 
> > Unfortunately I had no design control over the system (Blackboard) - but was
> > definitely interested in what other are doing, etc.
> > 
> > Maybe I should say I want to handle 250 httpd and 300-500 mysql connections
> > per second (simultaneously -- whatever that means these days.)
> 
> Blackboard sucks.  anyway...
> 
> someone else asked about if you're using mod_perl and Apache::DBI
> (to cache the database connections).  both are important factors.
> mod_perl will (or should) speed things up a lot, but it'll also
> increase the size of the httpd's, sometimes dramatically, depending
> on what (Perl) modules are in the httpd's.  and of course what part
> of the httpd's are shared memory (if i said that right; i'm not
> quite yet a memory-usage guru).
> 
> example: you've got 250 httpd's, each using 30 Mb unshared memory
> (not atypical for a mod_perl server with a kazillion loaded Perl
> modules).  that's 7.5 Gb memory!  and we haven't even counted the
> mysqld's yet... but they'll typically be <5 Mb.
> 

I have to disagree. I currently have a client setup running mod_perl on
Red Hat with only 28MB of RAM. No I didn't miss a number, 28MB.  I am
not sure how that machine was configured and for all I know it could be
a VMWare virtual server, but in trying to determine a timeout issue I
realized they had not setup a startup.pl file to preload the modules. 
After adding the startup.pl the server was able to handle much more
concurrent traffic (total amount untested) despites its anemic RAM
allotment.

The total of unshared memory is closer to 5MB on my machines, how did
you arrive at the 30MB figure? Or should I ask what are you running?

I use a lot of modules and have Apache::ASP , Embperl and Mason
processed pages.  I also have PHP loaded along with SSL (all static) so
it isn't a trim server configuration to start with on my end.

Aaron

> to sum up, i don't think your mysqld-variable tuning's gonna have
> much effect.  or at least, other things are gonna have a lot more
> effect.
> --
> Steve Lane <sml at zfx.com>
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