[Opensim-dev] Opensim-dev Digest, Vol 13, Issue 14
steve l
salbiedermann at gmail.com
Wed Apr 15 18:03:41 UTC 2015
Hi!
Thank you everyone for your answers. It got me thinking again, and
generally that is dangerous!
Is part of our problem in that OS was designed originally quite a few years
ago and is still suffering from code that was written to satisfy the needs
of the old servers we had at the time. Is Legacy code holding us back?
Is OS actually still running 32 bit code in a 64 bit world? Might that be
our main bottleneck in getting frame rates up and it being able to handle
the new demands we put on it?
Maybe it is time to go through OpenSim bit by bit and see what we can
update and what we just don't need anymore. From what I have been hearing
from many sources there are a lot of little things that are really critical
issues from handling of the database to interactions and timings in Physics
to networking issues and the need to update to more stout components like
the internal web server.
Everyone will probably want me to blow me out of the water screaming and
yelling at me, but maybe it is time to take a hard look at what needs to be
done with our base system to bring it kicking and screaming into the second
decade of the 21st century!
I think a lot of the time we are just patching patches. We know how well
that works on car tires! Maybe it is time to put on some new tires and get
rid of some of our issues once and for all!
Steve LaVigne
On Wed, Apr 15, 2015 at 7:33 AM, <opensim-dev-request at opensimulator.org>
wrote:
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> Today's Topics:
>
> 1. Re: New MOSES Physics Video (UNCLASSIFIED)
> (Maxwell, Douglas CIV USARMY ARL (US))
> 2. Re: Opensim-dev Digest, Vol 13, Issue 13 (steve l)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 15 Apr 2015 14:20:55 +0000
> From: "Maxwell, Douglas CIV USARMY ARL (US)"
> <douglas.maxwell3.civ at mail.mil>
> To: "opensim-dev at opensimulator.org" <opensim-dev at opensimulator.org>
> Subject: Re: [Opensim-dev] New MOSES Physics Video (UNCLASSIFIED)
> Message-ID:
> <
> 180878FAC40F8447ADED7BA2DE0775FD33CA19E4 at ugunhpso.easf.csd.disa.mil>
> Content-Type: text/plain; charset="utf-8"
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
> 1. This is an excellent point that illustrates just how wickedly complex
> our problem is. The short answer is "yes", we could do it locally.
> However, the distribution of the shared experience is a hard requirement
> and the final state of the bricks must be accurately portrayed to all
> client connections. One way to handle this is to treat this like a state
> machine and make sure all clients have precisely the same start conditions
> and then apply the same physics calculations. Theoretically, we would have
> the same end conditions. Afterward, we could queue the state changes of
> all the object and then have an arbitration process at the server make sure
> everything is actually at the same global location and orientation.
>
> This is a complex issue as it is contrary to the current world state model
> and would require the server to temporarily relinquish control of prims
> during the physics action, then take it back after steady state.
>
> 3. Our PhysX work is simply to ensure the physics calculations we need in
> the 83ms interval is actually completed and not dropped. It is address any
> "rubber banding" effects you see. It should also address jitter. It is a
> balance between update rate, network saturation, and QoS.
>
> 4. The DSG middleware approach gave us many insights into how a truly
> distributed simulator could work. That was extremely valuable work for us
> and we were privileged to have excellent collaborators in Intel and a
> strong community of MOSES users willing to help us test.
>
> v/r -douglas
>
> Douglas Maxwell, MSME
> Science and Technology Manager
> Virtual World Strategic Applications
> U.S. Army Research Lab
> Simulation & Training Technology Center (STTC)
> (c) (407) 242-0209
>
>
>
> -----Original Message-----
> From: opensim-dev-bounces at opensimulator.org [mailto:
> opensim-dev-bounces at opensimulator.org] On Behalf Of Mister Blue
> Sent: Wednesday, April 15, 2015 12:21 AM
> To: opensim-dev
> Subject: Re: [Opensim-dev] New MOSES Physics Video
>
> 1. Is the explosion of blocks or prims something that the viewer can
> handle? Or is this too tricky to make happen with the wide variations of
> machine running viewers and even more so that soon the viewer will run in a
> web browser?
> It is something a viewer could do but I don't know what mechanism could be
> used in the existing viewer.
>
>
> 2. Is there a way to make the explosion an overlay streaming event that
> runs over the current screen? - Just a crazy idea.... I am thinking of this
> more on a browser-viewer as that needs to run on devices that would have
> issues processing all that...
> In interesting idea but, again, would be viewer modifications.
>
>
> 3. Is it possible to make OS Physics run faster than 11FPS?
> Yes. The default configuration is for the simulator heartbeat time to be
> 11FPS and for the physics engine to be in sync. You can change the
> simulator heartbeat time but there are some known problems with that (too
> many assumptions in some places). If you run BulletSim on its own thread,
> you can speed up BulletSim but that would just make more updates.
>
>
> 4. It seems that the number of avatars exponentially changes the workload
> here. Maybe a graphics server could be designed as a sub service to handle
> that type of load, maybe running on a GPU instead of a CPU? It just seems
> to me that with all the other things that the region server has to do,
> offloading some of the heavy lifting would be a good thing. Maybe it is
> time to think of an OS "Pro" level of setup that separates the workload a
> bit more would be a good idea
>
> That was the design of DSG. For client connections, the simulator fed on
> client manager who multiplied the connection to multiple viewers. So you
> could have a simulator feeding 10 client managers who were each feeding 30
> viewers for a total of 300 connections. DSG also run script and physics
> servers to off load the central server from the computation from those
> operations.
>
>
> == mb
>
> On Tue, Apr 14, 2015 at 1:49 PM, Dahlia Trimble <dahliatrimble at gmail.com>
> wrote:
>
>
> I believe there is a means in the LLUDP protocol to stuff many
> updates for many objects into a single packet, though I'm not sure
> OpenSimulator is smart enough to do it in your simulation. It may be a way
> to improve networking performance quite a bit when may physical objects
> change velocity during the same simulation frame.
>
>
> On Tue, Apr 14, 2015 at 1:44 PM, steve l <salbiedermann at gmail.com>
> wrote:
>
>
> Hi!
>
>
> Robert- Thanks for the answer and the thought you put into
> it!
>
>
> So I am going to play dummy (Not far from the truth!)
> here. This means that we need to do re-writing on several parts of OS to
> speed things up and eliminate bottlenecks. a couple of questions then.
>
>
> 1. Is the explosion of blocks or prims something that the
> viewer can handle? Or is this too tricky to make happen with the wide
> variations of machine running viewers and even more so that soon the viewer
> will run in a web browser?
>
>
> 2. Is there a way to make the explosion an overlay
> streaming event that runs over the current screen? - Just a crazy idea....
> I am thinking of this more on a browser-viewer as that needs to run on
> devices that would have issues processing all that...
>
>
> 3. Is it possible to make OS Physics run faster than 11FPS?
>
>
> 4. It seems that the number of avatars exponentially
> changes the workload here. Maybe a graphics server could be designed as a
> sub service to handle that type of load, maybe running on a GPU instead of
> a CPU? It just seems to me that with all the other things that the region
> server has to do, offloading some of the heavy lifting would be a good
> thing. Maybe it is time to think of an OS "Pro" level of setup that
> separates the workload a bit more would be a good idea.
>
>
> These things always get me thinking...!
>
>
> Steve LaVigne
>
> A Dimension Beyond, Inc.
>
> www.adimensionbeyond.com
>
>
> On Tue, Apr 14, 2015 at 10:45 AM, Adams, Robert <
> robert.adams at intel.com> wrote:
>
>
> I don?t think the only problem is finding a
> physics engine that can handle 240 moving objects. Another is optimizing
> the updates from the physics engine.
>
>
>
> Think of the whole pipeline: the physics engine
> computes interactions and new locations/rotations for each object. That
> position update is sent to the simulator. The simulator updates the object
> data structures and sets an update flag. The location/position update is
> noticed and an update packet[1] is created and placed in output queues for
> each viewer. At some time, the packet is transmitted to each viewer.
>
>
>
> The update processing time can easily be more than
> the physics engine time.
>
>
>
> The OpenSimulator physics engines are run 11 times
> a second so they generate 11 position updates a second for each moving
> object. So, even an efficient physics engine will generate (240 * 11)
> updates per second which then turn into (240 * 11 * numberOfAvatars)
> packets sent per second.
>
>
>
> There are many optimizations possible in this
> chain.
>
>
>
> -- mb
>
>
>
> [1] This is technically wrong for the current
> version of OpenSimulator. For the technically inclined, an ?update needed?
> packet is put in the output queue and the actual packet to transmit is
> created when it is time to send the update. This is done because the update
> output packet queue can get long and the position/location information can
> be stale if multiple updates are in the queue. Only one ?update needed?
> packet is put in the queue and the current object location/rotation is put
> in the transmitted packet at the time of transmission.
>
>
>
> From: owner-moses-list at lists.mitre.org [mailto:
> owner-moses-list at lists.mitre.org] On Behalf Of steve l
> Sent: Tuesday, April 14, 2015 8:09 AM
> To: Michael Emory Cerquoni
> Cc: opensim-dev at opensimulator.org;
> moses-list at lists.mitre.org
> Subject: Re: [Opensim-dev] New MOSES Physics Video
>
>
>
> Hi!
>
> An excellent video on the physics of exploding
> grenades and the wall. On the OS Dev list Mister Blue has an excellent
> observation that the server crashes are due to the extreme amount of
> changes that have to be sent to every avatar. His idea of a client side
> solution might just be a good one. In the end is there any way that OpenSim
> can handle more events than that in it's present form? Is there any physics
> engine that can handle 240 moving scripted objects moving at once without
> lag?
>
> If we could get OS to the point that it would
> handle this load easily, we would have all our load issues solved!
>
> Steve LaVigne
>
>
>
> On Tue, Apr 14, 2015 at 6:33 AM, Michael Emory
> Cerquoni <nebadon2025 at gmail.com> wrote:
>
> Could these test scripts be shared so testing
> against other engines can occur as well, I would be interested to see how
> this same test goes against ODE and BulletSim as well.
>
>
>
> On Tue, Apr 14, 2015 at 8:18 AM, Maxwell, Douglas
> CIV USARMY ARL (US) <douglas.maxwell3.civ at mail.mil> wrote:
>
> Good Morning, as you all know the MOSES
> developers are working on PhysX integration into the Open Simulator to
> support functionality currently not possible in the platform. We are a
> methodical group and a couple months ago I asked one of our interns to work
> with the developers to create a series of baseline physics behavior case
> studies. The first case study is a destructible wall caused by an
> explosive charge. This wall is composed of blocks that are tested at a
> high density and a low density to simulate different destruction effects.
>
>
>
> The goal here is to eventually have all of
> the prims in the sim loaded with the scripts needed to react to any type of
> random explosive charge set by the participants in the training scenario.
>
>
>
> The video can be found below:
>
>
>
> https://youtu.be/jSofWcwWi7g
> <blockedhttps://youtu.be/jSofWcwWi7g>
>
>
>
> Your feedback is welcome.
>
>
>
> Observations:
>
> 1) Current limitations of the open
> simulator prevent us from expanding the tests beyond a simple wall.
>
> 2) The scripts exercise the engine well
> and expose limitations between the sim frame rate and the physics frame
> rate.
>
> 3) It is easy to crash the sim with this
> demonstration, especially if more than a handful of people are present
> (more than 3-4 client connections).
>
>
>
> Douglas Maxwell, MSME
> Science and Technology Manager
> Virtual World Strategic Applications
> U.S. Army Research Lab
>
> Human Research & Engineering Directorate
> Simulation & Training Technology Center
> (c) (407) 242-0209
> <blockedtel:%28407%29%20242-0209>
>
>
>
>
> _______________________________________________
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> Opensim-dev at opensimulator.org
>
> http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
> <blockedhttp://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev>
>
>
>
>
> --
>
> Michael Emory Cerquoni
>
>
>
>
>
> _______________________________________________
> Opensim-dev mailing list
> Opensim-dev at opensimulator.org
>
> http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
> <blockedhttp://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev>
>
>
>
>
>
> _______________________________________________
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> http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
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>
>
>
>
> Classification: UNCLASSIFIED
> Caveats: NONE
>
>
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> ------------------------------
>
> Message: 2
> Date: Wed, 15 Apr 2015 07:33:11 -0700
> From: steve l <salbiedermann at gmail.com>
> To: opensim-dev at opensimulator.org
> Subject: Re: [Opensim-dev] Opensim-dev Digest, Vol 13, Issue 13
> Message-ID:
> <CAB38sFg2m8qtfeHdFCQcuavpBq5tVDQ609MJJ67bDCiT2Mh=
> dw at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Thanks Ai!
>
> It is interesting that we were doing this apparently really well 10 years
> ago! Apparently in so many ways we have to reinvent the wheel over and
> over!
>
> Maybe we need to get ahold of these guys and see if they will share...
>
> Steve LaVigne
> A Dimension Beyond, Inc.
> www.adimensionbeyond.com
>
> On Wed, Apr 15, 2015 at 5:00 AM, <opensim-dev-request at opensimulator.org>
> wrote:
>
> > Send Opensim-dev mailing list submissions to
> > opensim-dev at opensimulator.org
> >
> > To subscribe or unsubscribe via the World Wide Web, visit
> > http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
> > or, via email, send a message with subject or body 'help' to
> > opensim-dev-request at opensimulator.org
> >
> > You can reach the person managing the list at
> > opensim-dev-owner at opensimulator.org
> >
> > When replying, please edit your Subject line so it is more specific
> > than "Re: Contents of Opensim-dev digest..."
> >
> >
> > Today's Topics:
> >
> > 1. Re: New MOSES Physics Video (Ai Austin)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Wed, 15 Apr 2015 09:59:23 +0100
> > From: Ai Austin <ai.ai.austin at gmail.com>
> > To: opensim-dev at opensimulator.org
> > Subject: Re: [Opensim-dev] New MOSES Physics Video
> > Message-ID: <552e28de.ad3ec20a.7807.ffffc879 at mx.google.com>
> > Content-Type: text/plain; charset="us-ascii"; format=flowed
> >
> > I saw the suggestion that explosion "physical" effects like this
> > might be dealt with locally (e.g. in the same was as particle visual
> > effects) in each viewer and not as a shared phenomenon where the
> > position of all the parts are updated in everyone's viewer.
> >
> > Snow and lighting visual effects often can be approximated and
> > everyone has roughly the same sort of shared experience, modulo the
> > allowable and supportable graphical quality in each viewer..
> >
> > I am reminded though of an exercise I took part in using the Forterra
> > OLIVE when that was still being actively developed (I think it got
> > sold to SAIC and I have not heard much aboit it since)... it was a
> > training exercise for military staff manning a checkpoint, and I was
> > an observer through my avatar. The military folks being trained were
> > to watch fro suspicious activity, but also treat all people at the
> > checkpoint well... and also to deal with the aftermath of an attack..
> > rescue helicopter coming in with dust clouds from the ground and
> > all... it was very realistic. And I was very surprised, even though
> > my avatar was partially protected from the checkpoint area by a solid
> > wall, that an explosion injured me... the pieces flying hiring my arm
> > and me being rendered unconscious! Viewer blurring over and me being
> > almost out of it.
> >
> > This is an example of the use of virtual worlds where the shared
> > experience of what debris from an explosion goes and who it hits and
> > when is necessary. And I think may be typical of the sort of thing
> > MOSES is seeking to achieve for realistic simulated
> > training. Interestingly Forterra OLIVE was itself originally
> > developed on a project for the US Army also more than a decade ago.
> >
> > Clearly there needs to be some consideration of the granularity of
> > physics and position updates across all users that are present in the
> > area and a consideration of how many parts of an exploding object
> > can be made physical and updates sent and at what rate. This could
> > be a simply enormous quantity of data and updates as others have
> > pointed out... so its not surprising that more avatars leads to
> > slower performance. Crashes nonetheless indicates something that is
> amiss.
> >
> >
> >
> > ------------------------------
> >
> > _______________________________________________
> > Opensim-dev mailing list
> > Opensim-dev at opensimulator.org
> > http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
> >
> >
> > End of Opensim-dev Digest, Vol 13, Issue 13
> > *******************************************
> >
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