Re: Biiig machines with pmix3-ips.pl

On Wed, 29 Nov 2000, Thomas Proell wrote:

> I want to run polygraph on (very?) big machines (dual P3 / 512MB).
> Unfortunately I don't have many of them, but I want to generate as
> much realistic load as possible.
> I'm about to set up the alias-IP-addresses, but the pmix3-ips.pl
> tells me to use only a maximum of 400 robots on one client. 
> 
> Why? Is this recommended, or what's up? Even on a 80386 it
> will tell me to use 400 robots. 

The number of aliases/robots is 1000. 400 is the load (req/sec). 

These per-host limits are required by PolyMix-2,3 rules to make the
results comparable and reproduceable. The actual values were selected
so that an average PC can handle the load even if a proxy gets behind
from time to time.

No interesting PolyMix variables depend on your host capabilities.
This is probably a good thing because it makes comparisons easier.
Custom workloads do not have to follow PolyMix rules, of course (see
below).

> Isn't there a better aproximation then that? 

Approximation of what?

> Can I simply change the constant to another value? What value
> would you suggest?

You sure can violate PolyMix-3 requirements and use as many robots per
machine as your hardware and OS can support. The only "real"
difference that I can see is in the number of MAC addresses and ports.
Whether that difference is important is impossible to say in general.

Note that using more than 2000-2500 robots on fast Ethernet is
probably not a good idea as you will hit the network bandwidth limit.

To estimate the maximum number of robots per host, I would suggest to
run a [relatively short] no-proxy test and compare performance
(response time) in idle and top phases. The response time change
should be negligible.

Alex.