[Opensim-dev] Sim and Phys Frames per Second (FPS) Issues
Diva Canto
diva at metaverseink.com
Mon Mar 2 21:10:11 UTC 2015
This has nothing to do with the viewer's fps. This is the tick of
simulation, the rate at which state changes. Last time I checked, this
was on an 89ms timer. There's not much gain in increasing this rate.
On 3/2/2015 1:00 PM, Mike Chase 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
>> <mailto: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
>> <mailto: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 <mailto: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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>>
>>
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