[Opensim-dev] [Non-DoD Source] Re: PhysX vs. BulletSim vs. ODE

Sat Feb 6 01:07:32 UTC 2016

I am very interested in testing out the physics system.  But the big
question is, is there any requirements past the basic opensim requirements
to have it working on another grid?

On Fri, Feb 5, 2016 at 1:27 PM, Zadark Portal <zadarkportal at gmail.com>
wrote:

> Hello Douglas
> Interesting progress report. Is there any timeline available for if or
> when others can configure and profile the system?
> Zadark
>
> On 5 February 2016 at 18:00, Maxwell, Douglas CIV USARMY RDECOM ARL (US) <
> douglas.maxwell3.civ at mail.mil> wrote:
>
>> Thank you for your feedback, Michael.  As you know, the OpenSimulator is
>> a very complex system.  It is very important for us to isolate as many
>> variables as possible to present a responsible comparison analysis of the
>> three engines.  Sean presented the performance of the engines with the
>> OpenSim configured as "stock".
>>
>>
>>
>> You are absolutely correct, using the "UseSeparatePhysicsThread" flag
>> does improve performance.  It is just one of the variables we are examining
>> to determine the affect of the physics engine on the overall system.  Sean
>> was reporting that there were significant increases in performance during
>> the baseline testing.  By carefully and systematically changing the
>> variables in the system, we can determine which variables have the most
>> impact differentiation from the baseline as well as what affect each
>> variable has on each engine.
>>
>>
>>
>> I realize this looks like tedious work, and it is.  However this approach
>> allows us to profile and examine the code so that meaningful changes can be
>> made for the better (not accidentally stumbling upon a combination of
>> variables).    As an Enterprise level user, we need the ability to predict
>> how the simulator will behave under different loads so we can plan and
>> provision for different usage scenarios.
>>
>>
>>
>> In the very near future we will be releasing our distributed PhysX code
>> as well.  This functionality will allow you to dedicate a separate server
>> to the physics engine and scale it vertically as appropriate.  We can
>> discuss the implications for scaled performance as well as tradeoffs in
>> network performance at that time.
>>
>>
>>
>> Lastly, we have specific needs that BulletSim cannot accommodate.  The
>> decision to choose PhysX for integration was done deliberately.  If you
>> would like to join us at the MOSES office hours or contact me directly, we
>> can discuss in detail.
>>
>>
>>
>> Have a great weekend.  v/r -doug
>>
>>
>>
>>
>>
>>
>> Douglas Maxwell, Ph.D.
>> Science and Technology Manager
>> Virtual World Strategic Applications
>> U.S. Army Research Lab
>> Human Research & Engineering Directorate
>> (c) (407) 242-0209 <%28407%29%20242-0209>
>> ------------------------------
>> *From:* opensim-dev-bounces at opensimulator.org [
>> opensim-dev-bounces at opensimulator.org] on behalf of Michael Emory
>> Cerquoni [nebadon2025 at gmail.com]
>> *Sent:* Wednesday, February 03, 2016 11:10 AM
>> *To:* opensim-dev at opensimulator.org
>> *Subject:* [Non-DoD Source] Re: [Opensim-dev] PhysX vs. BulletSim vs. ODE
>>
>> All active links contained in this email were disabled. Please verify the
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>>
>> ------------------------------
>>
>>
>> I have had over 100,000 physical spheres in Bulletsim without a crash and
>> was still able to log in, move around and erase all the objects and have
>> performance go back to normal, you need to enable running it in its own
>> Thread, to achieve this level of performance. to enable this feature in the
>> [BulletSim] section of OpenSim.ini add :
>>
>> UseSeparatePhysicsThread = true
>>
>>
>> On Wed, Feb 3, 2016 at 10:56 AM, Sean M <mondesire.sean at gmail.com
>>  < Caution-mailto:mondesire.sean at gmail.com > > wrote:
>>
>>> Greetings,
>>>
>>> The MOSES Team has been working on integrating NVIDIA's PhysX physics
>>> engine into OpenSim. Once complete, this integration will give OpenSim grid
>>> administrators the option of selecting the new engine for their own worlds.
>>>
>>> Prior to releasing the complete integration, the team has begun
>>> extensively testing and analyzing the engine's performance. We are pleased
>>> to report that PhysX significantly improves OpenSim's ability to support
>>> more physical objects than BulletSim and ODE. Our analysis ran under
>>> controlled and repeated testing (30 independent OpenSim executions per
>>> engine) that isolated physics engine related variables. Under these
>>> conditions, PhysX supported 86% more physical objects than BulletSim (the
>>> OpenSim default physics engine) before the simulation's performance starts
>>> to noticeable degrade. More specifically, before dropping below 9
>>> simulation frames per second (SimFPS), PhysX supported 3,300 physical
>>> objects (AtvPrm), BulletSim 1,800, and ODE 200. The reported SimFPS did not
>>> use the correction factor; therefore, the highest frame rate was 11.33
>>> frames per second. Attached is a graph of the performance of the three
>>> physics engines as 5,000 physical objects were generated in the simulation.
>>> All experiment details will be available in the 2016 proceedings of MODSIM
>>> World.
>>>
>>> Again, we are very pleased with the result and believe everyone will
>>> benefit from the effort. An announcement will be made in a few days to
>>> indicate when the final integration code will be available on the MOSES
>>> public GitHub.
>>>
>>> Thank you,
>>> Sean Mondesire
>>> MOSES Team
>>>
>>> [image: Inline image 1]
>>>
>>> _______________________________________________
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>>> Opensim-dev at opensimulator.org >
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>>>  < Caution-http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
>>>  >
>>>
>>>
>>
>>
>> --
>> Michael Emory Cerquoni
>>
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>>
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