[Zope] Performance requirements and ZEO

[J Cameron Cooper]

>
>
>Here's the question: is there any benefit to having dual-processor machines
>on any of these?  I think we can afford 3 of them, if necessary, but is it
>even needed?  I was planning on going with Dual-Xeon 2.8 GHz boxes running
>Linux.  I'd rather not run more than one instance of Zope on the clients,
>btw.
>  
>
Even if Python threads *loved* multiple processors, I usually find SMP 
to be less than optimal. You can do the math for yourself when you get 
your quotes, remembering that two processors will compute significantly 
below 200% of a single processor no matter what you do.

My strategy: Get a good solid server for your ZEO server. Run the ZEO 
client on this one too, and see if you can get away with it. If not, add 
cheapo web servers with ZEO clients until you're comfortable with the 
load. If you're clever, these might not even need disks. (See Knoppix.) 
Sure, they aren't serious machines, and they might fail. But who cares? 
You have bunches of them!

If you run Zope on a mulitple processor system, run one ZEO client per 
processor, and set processor affinity if you can. (Solaris can, and so 
can newer Linux kernels .) You may not like this much, but it's not so 
bad if you use zopectl or something like it.

And remember, Zope will benefit a LOT more from extra memory than from 
extra processors.

          --jcc

-- 
"My point and period will be throughly wrought,
Or well or ill, as this day's battle's fought."