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

Mon Mar 2 21:02:48 UTC 2015

There is no bottleneck, it is the target value. The simulation is designed
to run at this rate.

On Mon, Mar 2, 2015 at 1:00 PM, Mike Chase <
mike.chase at alternatemetaverse.com> wrote:

>  11 does seem really low.  I suppose someone has profiled this in the
> past.  Any idea what the bottleneck is.
>
> Mike
>
>
> On 3/2/15 3:54 PM, Dahlia Trimble wrote:
>
>  I believe 11 sim FPS is the target value. It would probably never go
> above this, but a number consistently lower than 11 fps would indicate
> performance problems. If the "lie" is simply a linear scaling, then it
> would have no impact in the ability to use the number as a comparitive
> statistic. since all such numbers would be similarly scaled.
>
>  I also believe some of these numbers eventually make it to the viewers
> and are used to adjust moving entity velocity when the sim is running
> slowly. I'm not sure of the exact path but I think "time dilation" is
> involved. Altering these values may induced undesirable movement effects
> when the simulator is running slower than normal.
>
>  Raising the target above 11 would also likely induce issues as other
> parts of the code assume 11 is the target.
>
> On Mon, Mar 2, 2015 at 11:16 AM, Sean M <mondesire.sean at gmail.com> 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.
>>>>
>>>> _______________________________________________
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>>>>
>>>>
>>>
>>>
>>> --
>>> Michael Emory Cerquoni
>>>
>>>
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