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OFF
06-14-2006, 11:45 PM
After i'm upgrade my pc (now it AMDX2 3800+) and making a few tests, i saw that radiosity is not affect by multicore processors. In the render options Multithread set to 4.

Weepul
06-15-2006, 12:14 AM
This has always been the case. The calculation of the preliminary solution is not multithreaded, never has been. It'd sure be nice if it was, but it's not.

mattclary
06-15-2006, 05:15 AM
Without testing it for myself, I'm not going to say you are wrong weepul, but, IMO, if mutliple threads were NOT being used, then one core would be pegged, and the other core would not be utilized. Looking at his screen shots, both cores are utilized 50%.

OFF, how long does the preliminary calculations take? I assume that IS what you mean? When rendering both cores go to max usage, right?

Lightwolf
06-15-2006, 05:37 AM
Without testing it for myself, I'm not going to say you are wrong weepul, but, IMO, if mutliple threads were NOT being used, then one core would be pegged, and the other core would not be utilized. Looking at his screen shots, both cores are utilized 50%.
No, the screenshot is fine. Due to the way the task scheduling works, a single threaded task can move from one core to the other (unless you manually tell the OS to run the app on one dedicated core only).

This is mainly because the thread never just runs without inerruption, there are a lot of interruption where the OS momentarily stops the thread to do other tasks (well, the task scheduler to be more precise). When continuing the render thread it may move it to another core.

Cheers,
Mike

lots
06-15-2006, 09:22 PM
Makes you wonder what the original reason for the preliminary computations to be single threaded was...

OFF
06-16-2006, 07:48 PM
squzee for post in this thread

Lightwolf
06-17-2006, 04:25 AM
Makes you wonder what the original reason for the preliminary computations to be single threaded was...
Ease of programming :)
One some cases it is much easier to do things in a single thread, especially if one computation depends on another.
Keeping multiple threads in sync when working on a common set of data (especially if the threads modify the data, something rendering doesn't currently do) is not an easy task.

Cheers,
Mike

Captain Obvious
06-17-2006, 06:23 AM
especially if the threads modify the data, something rendering doesn't currently do
An irradiance caching prepass might actually do just that, depending on how it works. And voxelization or BSP-tree-creation also create and modify data. Is the "raytracing optimization" in Lightwave multi-threaded?

Lightwolf
06-17-2006, 07:03 AM
Is the "raytracing optimization" in Lightwave multi-threaded?
As far as I know... no. Neither in 8.0 nor the kd-tree generation on LW 9.0. I don't find it that bad though, it seems the kd-tree is very fast, even for mult-million poly scenes.

Cheers,
Mike

Captain Obvious
06-17-2006, 08:02 AM
Even if it was multi-threaded, you wouldn't save all that much time. Even if it was very slow, I doubt the Kd-tree would take more than 10-15 seconds to generate. If the scene takes half an hour to render, the 5 or so seconds you'd save by multi-threading it is hardly all that important.

Lightwolf
06-17-2006, 08:22 AM
Even if it was multi-threaded, you wouldn't save all that much time. Even if it was very slow, I doubt the Kd-tree would take more than 10-15 seconds to generate. If the scene takes half an hour to render, the 5 or so seconds you'd save by multi-threading it is hardly all that important.
Yeah, the kd-tree is no issue. Shadow maps are, especially if you render plenty of (relatively) fast passes (motion blur!). I've had cases where the shadow map generation would take longer than the actual rendering of the pass.

Then again, nobody seems to care for shadow maps nowadays anyhow :(

Cheers,
Mike

Captain Obvious
06-17-2006, 08:45 AM
Primitive shadow maps ā la Lightwave? I can see why people don't care for them. ;) Deep shadow maps, on the other hand, are probably great.

Lightwolf
06-17-2006, 08:48 AM
Primitive shadow maps ā la Lightwave? I can see why people don't care for them. ;) Deep shadow maps, on the other hand, are probably great.
Hey, if you have thousands of frames to render in no time, you take anything to shave off time ;)
Deep shadow maps would indeed be grand, hard to do since they are patented by Pixar (which didn't stop others from implementing similar techniques).

Cheers,
Mike

Captain Obvious
06-17-2006, 09:18 AM
I really should learn how to program rendering technology and start a company. No software patents of any kind in Sweden. Pardon my saying so, but w00t! :thumbsup: So what if Pixar has patented deep shadow maps? That only applies in the US and a few other places.

Lightwolf
06-17-2006, 10:09 AM
That only applies in the US and a few other places.
I guess the problems really start once you export... or grow large enough to actually have a distributor sitting in a country that suffers from software patents.

Cheers,
Mike

Captain Obvious
06-17-2006, 10:52 AM
Yeah, but that's why you only release it via Torrent sites! ;)

Lightwolf
06-17-2006, 11:04 AM
Yeah, but that's why you only release it via Torrent sites! ;)
Lol... yeah, not only do you guys don't follow the stupid software patents, but you're a bit more level headed on copyright issues as well... :D

Cheers,
Mike

Captain Obvious
06-17-2006, 01:00 PM
Well, we used to be that way, anyway, until Bodström got in charge. Know what happened to the Pirate Bay? Probably. Did you also know it happened because the RIAA (or was that the MPAA?) asked us. I don't know, but something strikes me as very very rotten when a foreign industry lobby group can badger the swedish authorities into closing down a site that isn't technically breaking swedish law. And as if that wasn't enough, the police also stole servers belonging to completely unrelated companies. The only "crime" they were guilty of was that they rented the same locale as the Pirate Bay. I'm starting to consider moving to Norway... :(

Sorry for the rant.

Lightwolf
06-17-2006, 01:16 PM
Sorry for the rant.
No worries. And yes, what happened to them has been followed quite closely abroad :)

Cheers,
Mike