What may cause 5+1 = 10 Landimpact?

[gweha]

I try to figure out what can possibly make 7 items linked making 5LI  total linked before but adding + 1LI combination on top of it, making it 10 Land Impact?

What may be wrong there?

 

[Beq Janus]

Are all the items mesh?

If one or more is a prim/sculpt then linking it into a linkset, may cause the legacy prim cap to be lifted if any of the other items in thelinkset have materials or alpha mask enabled.

Edited March 23, 2022 by Beq Janus
add more

[gweha]

that must be something like that then. Because it is so weird Download 1.1 , Physics 0.1 , Server 10.0. . 

So is this considered a bug?

 

 

Edited March 24, 2022 by gweha

[animats]

1 hour ago, gweha said:

So is this considered a bug?

No. It's a backwards compatibility feature.

Originally, all prims had 1 LI. Then came mesh, and with it, the "new accounting system". To prevent breaking old items, classic prims are still 1 LI. But as soon as you use any fancy features, like materials, the "new accounting system" which involves counting triangles, takes over. If you link two things together, and one is on the new accounting system, the whole linkset gets charged LI according to the new accounting system.

It's a pain, but it doesn't break existing content. Which was the whole point.

[ChinRey]

5 hours ago, animats said:

No. It's a backwards compatibility feature.

Yes but that doesn't make sense in this case:

6 hours ago, gweha said:

that must be something like that then. Because it is so weird Download 1.1 , Physics 0.1 , Server 10.0.

Unless the linkset is crammed full of active scripts, those weights mean the land impact is 10 according to the new calculation and 20 according to the old. So how on earth could it have been 5+1 to begin with?

Edit: A linkset with six part and server weight 10 will have to have 28(!) active scripts running. A seven part linkset with 5 LI and download and physics weights as low as this must contain 4-7 active scripts. So if that 1 LI object added is a single prim (not mesh) with 21-24 active scripts it will add up. But please, don't tell me that's the explanation!

Edited March 24, 2022 by ChinRey

[arton Rotaru]

2 hours ago, ChinRey said:

But please, don't tell me that's the explanation!

Unlikely.

Adding scripts will only increase the server weight to the number of links. After that you can add as many scripts as you like, it won't go any higher.

According to the description, the 7 part set must have a server weight of 5. Which is possible by adding scripts.
The 1 LI part can be no more than 2 links, because 3 would make it 1.5 server, which would be 2 LI.

So 7 + 2 = 9. Even with a 1000 scripts, it would have a max server weight of 9.
 

[ChinRey]

50 minutes ago, arton Rotaru said:

Unlikely.

Adding scripts will only increase the server weight to the number of links. After that you can add as many scripts as you like, it won't go any higher.

Oh I forgot that. But that means it is impossible for a linkset with only eight parts to have a download weight as high as 10 so something is wrong here. @gweha, can you give us a bit more information about this object? A screenshot of the popup window showing the weights would have been particularly useful.

 

53 minutes ago, arton Rotaru said:

The 1 LI part can be no more than 2 links, because 3 would make it 1.5 server, which would be 2 LI.

Yes, except if it had two parts and still counted as 1 LI, both parts would already have been on the modern land impact calculation so there wouldn't have been any huge jump in LI when they were linked.

[arton Rotaru]

6 minutes ago, ChinRey said:

...so something is wrong here.

Yes. A bug is pretty unlikely. Because, if so, we all would seeing it. So something about gweha's  description must be wrong.

[Beq Janus]

1 hour ago, arton Rotaru said:

Yes. A bug is pretty unlikely. Because, if so, we all would seeing it. So something about gweha's  description must be wrong.

I visited Gweha. After some puzzlement I found the answer and learned something new. win/win.

Her linkset is made up of a number of parts

a floor, a ring of "hooks" that curves overhead and then  a series of particle target prims that are needed for some chains.

The final ingredient is a very script heavy box in which she has all her normal animations etc. that go into her furniture.

The script box has a server weight of 1.0 the other parts are all 0.5

however, when linked together all the individual links (prims or mesh) act as if they have a server weight of 1.0 each

Thus when she links all the parts together before the box. we have 9*0.5, total server cost of 4.5, and that being lower than the other costs the LI is 7 because of the download weight. So far so good, everything as expected.

Now we link the green box. we expect it to add 1 as the server weight is shown as 1.0

The LI magically becomes 10 as she stated, which suspiciously, matches the number of links in the linkset. hmmm

I tested it with a few prims and sure enough , linking the box of scripts forces the server cost to be set to the number off links in the linkset.

I had thought that the server cost was dark art and we didn't have any good information on it, but google proved me wrong and I found this.

https://wiki.secondlife.com/wiki/Mesh/Mesh_Server_Weight

Specifically the note in yellow

Quote

MIN{ (0.5*num_prims) + (0.25 * num_scripts), num_prims }

and that completely explains the behaviour.

So if you have more than two times the number of scripts to the number of links in the linkset, then you'll hit the lower cap "num_prims".

In Gweh'a case 0.5*10 + 0.25 * LOTS > 10 so the server cost gets set to 10. 

The confusion arises because we have no indication of "potential server cost" in the "more info" display. when that box of scripts was standalone the content were still <big number> LI worth but it was capped at 1, by linking it the cap lifts to the size of the linkset.

I literally had no idea that was a thing. Thank you @gweha and hopefully we both learned.

@Monty Linden we have a number of anti-builder mines scattered around the place. This was a new one on me (and no doubt everyone else will be going duh Beq, 'course it does 🙂 )

"More info" typically warns you of the true underlying costs that the LI algorithm hides, It would be good to be able to reflect the true "potential" server cost in a way that  helps builders navigate through the minefields.

 

 

[Beq Janus]

5 hours ago, ChinRey said:

Edit: A linkset with six part and server weight 10 will have to have 28(!) active scripts running. A seven part linkset with 5 LI and download and physics weights as low as this must contain 4-7 active scripts. So if that 1 LI object added is a single prim (not mesh) with 21-24 active scripts it will add up. But please, don't tell me that's the explanation!

it was indeed. I had never dug into server costs like that, though you and @arton Rotaruwere clearly aware of it. 🙂

 

[gweha]

I used to like basic maths when 5 + 1 equals 6 😇

Thank you all and especially @Beq Janus for great help

 

Edited March 24, 2022 by gweha

[ChinRey]

29 minutes ago, gweha said:

I used to like basic maths when 5 + 1 equals 6 😇

This is Second Life, things aren't supposed to make sense here. I'm pretty sure that's in the TOS.

[ChinRey]

39 minutes ago, Beq Janus said:

it was indeed. I had never dug into server costs like that, though you and @arton Rotaruwere clearly aware of it. 🙂

Well, I learned it from Arton but I forgot that cap and even he didn't know about that extra quirk you uncovered.

[ChinRey]

1 hour ago, Beq Janus said:

In Gweh'a case 0.5*10 + 0.25 * LOTS > 10 so the server cost gets set to 10.

Ummm, for those of us who know our Pratchett, LOTS=16. (Besides, according to the original post num_prims could not have been higher than 9.)

 

[arton Rotaru]

2 hours ago, Beq Janus said:

The LI magically becomes 10 as she stated, which suspiciously, matches the number of links in the linkset. hmmm

I tested it with a few prims and sure enough , linking the box of scripts forces the server cost to be set to the number off links in the linkset.

Yeah. That's the expected behavior. The confusion arose from gweha's false description. As you say, the "7" part linkset was actually 9 links. 🙂

[arton Rotaru]

1 hour ago, ChinRey said:

Well, I learned it from Arton but I forgot that cap and even he didn't know about that extra quirk you uncovered.

It's no extra quirk at play here actually. 😇 Single prim, 1000 scripts = 1 server weight. 10 links, 1000 scripts = 10 server weight.

[Monty Linden]

3 hours ago, Beq Janus said:

@Monty Linden we have a number of anti-builder mines scattered around the place. This was a new one on me (and no doubt everyone else will be going duh Beq, 'course it does 🙂 )

Oh, dear god, do we.  I walked through that recently for the first time ever and despaired.  A non-linear function of three terms, one of which uses the result of a loose, converging (maybe) iteration.  I suspect that wiki page needs some updates but, yes, that is relevant.