[Opensim-dev] Sim and Phys Frames per Second (FPS) Issues

Mon Mar 2 21:33:54 UTC 2015

I think like Dahlia said, it may influence the viewer a bit which expects
55fps like SL offers, I believe the target was 11 because it was easy to
multiply to get 55, since 55 doesn’t divide nicely otherwise. but it also
probably doesn’t offer much benefit to adjust it either way up or down
since mono can only process threads so fast before it also flounders, would
not improve performance by just adjusting it alone, at this point it would
probably require a major overhaul to many data points make any changes here
that could be considered effective.

On Mon, Mar 2, 2015 at 4:31 PM, Diva Canto <diva at metaverseink.com> wrote:

>  BTW, I don't know why the stats reporter multiplies by a factor, maybe to
> stay backwards compatible with some perception that people expected?
> Simulation FPS is supposed to be constant. In the case of OpenSim, the user
> experience doesn't change if we increase this rate beyond 11/sec. If it
> goes below that, however, then that's a sign that the simulation is
> stressed.
>
> I refer anyone interested in this to documentation about simulations in
> general. Here's a good tutorial that I point students to in one of my
> courses:
> http://buildnewgames.com/real-time-multiplayer/
> Scroll down to the part about "game loops"
>
>
> On 3/2/2015 11:16 AM, Sean M wrote:
>
> There are 3 frame rates: *simulation*, *physics*, and *client*. Please,
> someone correct me if I am wrong: the *simulation fps* is how many
> simulation loops can be processed in a second, where each loop processes
> physics, scripting, region updates, etc; *physics* *fps* is just how many
> physics loops get processed per second, where each loop calculates
> collisions, gravity changes, and other movement updates for all appropriate
> objects in a region Both physics and simulation (phys/sim) fps are
> server-side. The fps the *client* is concerned with is graphics rendering
> on the viewer (firestorm, singularity, etc) and is literally how many
> visual frames/shots are displayed per second to the client. From a client
> point of view, 11fps is low because that is a low amount of image updates
> the client is visually seeing on their viewer. I am concerned with the
> simulation and physics FPSs being reported with highly inflated numbers. I
> want to use sim and phy FPSs as measures of how my region is performing but
> concerned that the correctionFactor of 5 is invalidly skewing these
> metrics, making both fps useless.
>
>  Michael, or anyone else, do you know why OpeSim ticks at 11 fps? Why 11?
> Is my understanding of what constitutes a "frame" correct?
>
> On Mon, Mar 2, 2015 at 1:37 PM, R.Gunther <rigun at rigutech.nl> wrote:
>
>>  11fps ? is that not very low. 22fps gives more rome or 33fps.
>> But i admit that i read fps maby wrong, and have nothing today with the
>> framerate or smoothness on the screen..
>>
>>
>>
>> On 2015-03-02 19:28, Michael Emory Cerquoni wrote:
>>
>> The reason physics and scripting are locked at 11fps is because this is
>> what the OpenSimulator heartbeat ticks at, the reason it is multiplied is
>> to satisfy the viewer statistics, I am not sure its possible to have it
>> report the legitimate numbers without some wierd side effects, but I could
>> be wrong, you would have to experiment, I suspect though that changing this
>> could lead to a lot of badness.
>>
>> On Mon, Mar 2, 2015 at 1:23 PM, Sean M <mondesire.sean at gmail.com> wrote:
>>
>>>  Greetings,
>>>
>>>  We at the MOSES project have noticed Simulation and Physics frames per
>>> second (FPS) have a few issues that we are trying to resolve. The issues
>>> are producing suspicious performance statistics for the analysis of the
>>> current version of OpenSim that we are running.
>>>
>>>  First, there is a correction
>>> factor (m_reportedFpsCorrectionFactor) that the raw SimFPS is multiplied
>>> by. The comment in the following line is a bit curious because it indicates
>>> that the FPS is artificially inflated to "lie" about the actual FPS being
>>> so low:
>>>
>>>  OpenSim/Region/Framework/Scenes/SimStatsReporter.cs: Line 317
>>>  // We're going to lie about the FPS because we've been lying since
>>> 2008.  The actual FPS is currently
>>> // locked at a maximum of 11.  Maybe at some point this can change so
>>> that we're not lying.
>>> int reportedFPS = (int)(m_fps * m_reportedFpsCorrectionFactor);
>>>
>>>  Also, lines 174 and 227 mention the use of this correction factor.
>>>
>>>  Second, this multiplier also comes into play in the Scene where there
>>> is a MinFrameTime, which seems to be the minimum reported amount of
>>> time to process a frame:
>>> OpenSim/Region/Framework/Scenes/Scene.cs:Line 723
>>>
>>>  Both of these variables, the correction factor and MinFrameTime, are
>>> concerning from a statistics view point as they are generating skewed and
>>> massaged numbers; therefore, I have a few questions:
>>>
>>>  1) Is it commonly known that Sim and Phy FPSs are inflated to maintain
>>> the "lie"? And if so, will it be corrected to be an accurate reporting of
>>> processed frames per second?
>>>
>>>  2) What exactly are the definitions for OpenSim's Simulation (Sim)
>>> FPS, Physics (Phy) FPS and a frame (I have found conflicting and vague
>>> definitions on the wiki)?
>>>
>>>  3) What are the known performance consequences of setting the m_reportedFpsCorrectionFactor
>>> to 1 and MinFrameTime to 0?
>>>
>>>  Thanks,
>>> Sean M.
>>>
>>> _______________________________________________
>>> Opensim-dev mailing list
>>> Opensim-dev at opensimulator.org
>>> http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
>>>
>>>
>>
>>
>> --
>> Michael Emory Cerquoni
>>
>>
>> _______________________________________________
>> Opensim-dev mailing listOpensim-dev at opensimulator.orghttp://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
>>
>>
>>
>> _______________________________________________
>> Opensim-dev mailing list
>> Opensim-dev at opensimulator.org
>> http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
>>
>>
>
>
> _______________________________________________
> Opensim-dev mailing listOpensim-dev at opensimulator.orghttp://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
>
>
>
> _______________________________________________
> Opensim-dev mailing list
> Opensim-dev at opensimulator.org
> http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
>
>

-- 
Michael Emory Cerquoni
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://opensimulator.org/pipermail/opensim-dev/attachments/20150302/940aa190/attachment-0001.html>