Script performance measuring

Ann Otoole missannotoole at
Thu Dec 17 09:04:34 PST 2009

"resource robbery"?  ARC has zero to do with sim lag or sim performance. ARC has to do with triangles/polygons rendered by your GPU.
And the direction appears to be in increasing triangle/polygon counts.
Case in point: Linden Lab's in house content developers built the new Linden Homes sims. Better have a really good computer to go there...
Check it out! 15 million triangles per frame! Crash there much?

ARC should be deprecated and replaced with a tutorial on ktris/fr since that is what "rendering cost" is all about. The adding of scripts to the ARC calculation revealed something about whoever created ARC. Scripts do not do anything to rendering cost unless they are altering the polygons or are changing the textures constantly and that would be minimal once cached. Certain funky things one can script with glow can also increase bandwidth utilization btw. There has been zero concern about scripts related to bandwidth utilization thus far.

So ARC needs to go and be replaced with:
1. An algorithm that computes ktris/fr and compares to GPU/VIDRAM/CPU/RAM/OS for a true render cost (since it is relative to the power of the computer). 
2. Sim Render Cost that computes the ktris/fr in view as per 1.
3. Avatar Render Cost that computes ktris/fr of the avatar and attachments as per 1.
4. Parcel Render Cost that computes ktris/fr of the parcel as per 1.
5. Parcel Script Cost for rezzed scripts in a parcel that computes based on memory over time and script time over time.
6. Sim Script Cost for rezzed scripts that computes based on memory over time and script time over time.
7. Avatar Script Cost for worn scripts that computes based on memory over time and script time over time.
8. Avatars in sim Cost for scripts worn by all avatars in the sim that computes based on memory over time and script time over time.
9. Most important: Script cost per script based on memory over time and script time over time.
10 An aggregate "Immersion Experience Cost" that gives an overall rollup value to indicate your odds of having a good experience with your hardware in the region you are in at any given time.

It is an error to asume "render cost" is as simple as the artificial value presented by the inherently flawed ARC algorithm. The issue is much more complex.

All we have today are some estate tools that exhibit issues with measurements themselves. But if you study a sim long enough you can "get a feel" for what symptoms correlate to the available measure. "Getting a feel" is hardly scientific method.

If your experience is suffering you can drop RenderMaxNodeSize down to 4192 or less but I don't recommend it since prims will simply derender in view on a random basis. I.e.; chunks of builds will vanish. And it still won't help much since the geometry is still available were you to edit the "vanished content". If you are having to go this route you should seriously consider a system upgrade.

If you are on high graphics windlight adds 130,000 triangles whether or not you can see the sky or water and that is usually far more than a necklace. So you can always turn off windlight (atmospheric shaders). But then you won't have the cool skies.

Here is some more info I finally decided to write down since it has to be endlessly repeated:

From: "AnnMarie at" <AnnMarie at>
To: SL Scripters <secondlifescripters at>
Sent: Thu, December 17, 2009 11:23:30 AM
Subject: Re: Script performance measuring

Agree, with 1.5 mainland sims we are at a serious disadvantage.  My main sim 
has been crashing 2 or 3 times a week and restarted on request 2 or 3 times 
a week when the lag is bad and time dilation down below 50%.  It seems 
perhaps that some of the scripts tend to load up the system over a period of 
time since a restart puts the time dilation back to 0.98.  But with no 
diagnostics all I can do is ask the concierge operator to tell me the top 
script offenders to try and identify problems.

I assume that this information is withheld from mainland dwellers so you 
can't see what your neighbor's are doing but there should be some way to get 
the information if you own the whole sim!.  Any diagnostic tools will be 
very welcome.  I hope they can be applied to no modify scripts too.

How informative a guide is the Avatar Rendering Cost?  I have one employee 
where we found that her necklace jumped her rendering cost from around 2,000 
to over 8500.  That is irresponsible resource robbery.

----- Original Message ----- 
From: "Jeremiah Whitfield" <jeremiah.whitfield at>

> As a mainland owner (half a sim) I don't have access to the features a
> private sim owner has to view the top scripts. I do quite a lot of
> scripting, including a free translator and I'm curious what
> possibilities there are to good a good insight into how much sim
> resources my scripts are using, other than going to an empty sim and
> looking at the sim statistics. I really tried to make my translator as
> lean as possible but since it's being used so much I'm always looking
> for ways to improve it's performance

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