[Zope] Re: Give it a rest + answers. (Re: Re: Zope + Apache on Quad Debian machine)

[Andrew Sawyers]

On Wed, 2006-03-22 at 08:24 -0500, Tres Seaver wrote:
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> WHile at ZC, one of the other engineers and I did some testing on SMB
> boxes, and found that "one appserver per CPU" gave us near linear
> scaling of the application, without any explicit affinity set.  I don't
> have the numbers (we were using stock Dell 1U dual CPU boxes, I think),
> but the win seemed clear enough that we quit invesigating taskset.
> 
The other engineer was me, and it was close enough to double the load
per instance, per cpu.  If he needs to test it, the numbers are easy to
get.  Run a single instance on a SMP Server, and hit it with load. You
will get Y.  Run another instance and spread that load across both
instances and you will get nearly 2xY.  Take a single cpu server and run
1 instance and load test it, and you'll get Y.  Take that same single
cpu server and run 2 instance, and load test it across both instances,
and you'll get Y.  These tests were done on both Linux and FreeBSD and
both were approximately the same.  The conclusion was, no further
complexity is required to get a substantial performance benfit by
running SMP Servers with multiple Zeo Clients instances, where the # of
CPUS == the # of Zeo Client instances.  This has been posted to the
lists serveral times BTW.

The only snafu is to make sure you have enough RAM to run several zeo
client instances.  If you've got a 4way server, I'd recommend 16GBs of
RAM if it's a big site.  I personally like to put as much ram into a
server as it can physically handle.

Andrew Sawyers
> 
> Tres.
> - --
> ===================================================================
> Tres Seaver          +1 202-558-7113          tseaver at palladion.com
> Palladion Software   "Excellence by Design"    http://palladion.com
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