[Opensim-users] PhyFPS

[Karen Palen]

Neither of these effects is unique to OpenSimulator - these exact same
problems occur in SecondLife and other virtual worlds.

The details are best asked of the developers, but my experience is that the
problem with scripts is that there can be hundreds or thousands of them
running at once!

There can also be badly written scripts, for example a hundred scripts that
all monitor the main chat channel every 0.1 sec will bog down that channel
badly.

The problem with collisions is a little more subtle. It essentially boils
down to figuring out which two objects could collide and figuring out when
they do collide (i.e. get within a certain distance of each other). Since
every point on every object could potentially collide with every point of
every other object in the sim you can see how the proble becomes huge very
quickly! If you consider surfaces rather than merely a collection of points
then the problem is even more complex since a surface is by its nature
derived from the point collection - requiring a certain CPU time to perform.

In essence handling of collisions boils down to sorting out those objects
(and points on those objects) which are likely to collide and allocating CPU
time efficiently.

Once again I don't believe that OpenSimulator is greatly different from
SecondLife in this, it is a problem that both share.

Clearly if OpenSimulator can run 1000 avatars on a sim then the collision
problem must be handled very well well indeed!

To address your last point, a far as I know there has been no formal
benchmarking either of OpenSimulator or of SecondLife to develop reliable
and realistic estimates of these numbers. What we do have are various "ad
hoc" reports in the Wiki plus the experience of people who have had lag
problems with a sim.

That being said it is also apparent that V0.7.X is a vast improvement over
every earlier version of OpenSimulator - 100X faster is certainly believable
in my experience.

Karen

On Thu, Sep 23, 2010 at 2:46 PM, Serendipity Seraph <sseraph at me.com> wrote:

>
> On Sep 22, 2010, at 9:39 PM, Karen Palen wrote:
>
> I can add one more datum point to this, I have the latest Diva distro
> (V0.7.0.2) standalone running on an Athlon triple core 3X 445 with very
> light cpu load up to 5 users - the most I have tried.  I documented this in
> the wiki running on my Intel I7 machine, but the MUCH lower performance low
> end Athlon (by about 200X!) is giving very similar results. The Athlon was
> simply chosen as the cheapest CPU on th e market last month (US$64) and has
> proven to be quite adequate for 10 regions.
>
> The major limit seems to be the IO bandwidth of my consumer cable
> connection. As noted previously, this dramatically increases CPU usage as
> the IO "maxes out".
>
> As Teravus commented, scripted objects and things like collisions make a
> far greater difference than the basic region maintenenace.
>
>
> Why would most scripts make that much difference unless they are still all
> getting a huge amount of memory?  Is the script engine that bad?  Does it
> have to be?    Since not that many things are usually moving about to
> collide it seems a bit odd that that would so much difference either.   How
> are these things validated?
>
> - seren
>
>
> Try it out for yourself on: http://mars-simulator.hobby-site.org:9000/wifi
>
> Karen
>
>
> On Wed, Sep 22, 2010 at 1:05 PM, Oliver Guerino <oguerino at gmail.com>wrote:
>
>> Hi,
>>
>> I have the OpenSim version 0.6.9 installed on a server QuadCore Xeon 2.0
>> with 12GB of RAM. When you have more than 20 avatars PhyFPS is connected
>> to around 35fps out why this might be happening?
>>
>> Oliver
>>
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