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

[Sean M]

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.
>>
>> _______________________________________________
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>> Opensim-dev at opensimulator.org
>> http://opensimulator.org/cgi-bin/mailman/listinfo/opensim-dev
>>
>>
>
>
> --
> Michael Emory Cerquoni
>
>
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