[Opensim-dev] forcing some load, kicking the tires

[Bowman, Mic]

i played with this some this afternoon (ode physics). i have about
50-100 pyramids that i loft up to a height of about 10m above a mountain
and let them drop (and repeat 1000 times). the load was never a problem
(at 50 the average CPU utilization is less than 50%). however... before
the iterations complete, the physics fails on each of the individual
objects (they get lofted but never fall) and the server throws an
exception in ODE (OdePlugin.cs line 533)... 

on a different note... i played around with different ways of writing
the script. without digging into the code too far, the issue with the
performance earlier certainly seemed to be related to handling of timer
events. 100 timers firing once a second or once every other second with
no physics causes *far* more load (and other bad behavior like dropping
updates) than handling the physics on 100+ objects rolling down a
mountain. 

--mic


-----Original Message-----
From: opensim-dev-bounces at lists.berlios.de
[mailto:opensim-dev-bounces at lists.berlios.de] On Behalf Of Sean Dague
Sent: Friday, November 09, 2007 11:21 AM
To: opensim-dev at lists.berlios.de
Subject: Re: [Opensim-dev] forcing some load, kicking the tires

On Fri, Nov 09, 2007 at 08:44:05AM -0800, Bowman, Mic wrote:
> 
> in order to test some aggregate networking issues, we have a
standalone
> server (current trunk version from svn, no physics, xp, core duo, 4G,
> ...) where we are moving a bunch of objects around inside a fixed
> region. each object is running a script with a timer event that fires
> every 1-3 seconds and the object moves to a random position using
> llsetpos (so there are no collisions). this set up gives us the
ability
> to generate scalable and almost reproducible loads (at least for
object
> updates).
> 
> with 30 objects in motion, the server runs < 30% load, cyclical
(athough
> the peak loads occur at about 15 second intervals so i'm not sure how
> that correlates to timer events). with 100 objects in motion the
server
> load peaks at around 75% (memory image is around 800M consistently).
> however, with 100 objects in motion, the bandwidth to the one user
> currently connected goes to (almost) 0, with periodic (every 10
seconds
> or so) big bursts of updates. 

I would suggest enabling ODE.  I think that the days of basic physics
being interesting are coming to an end now that we've got a physics
engine that works reasonably well.

It would also be interesting to see what the difference in load was
between it an basic physics.  I'm assuming 10x, but a real number there
would be good to have.

       -Sean

-- 
__________________________________________________________________

Sean Dague                                       Mid-Hudson Valley
sean at dague dot net                            Linux Users Group
http://dague.net                                 http://mhvlug.org

There is no silver bullet.  Plus, werewolves make better neighbors
than zombies, and they tend to keep the vampire population down.
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