Jump to content
The Dark Mod Forums

[Resolved in TDM 2.06] multi core-support


Darkman

Recommended Posts

Hey

 

there was a little simliar discussion in another topic some month ago, but none of the TDM-members entered there.

 

so, i wonder, if there is a plan to implement multi core-support someday?! i think the advantages would be obvious (and at the same time it could also become more necessary, f.e. think of the upcoming hdr-feature), whereas i dont know how difficult it is to code such a feature...

 

would be kind, if any of the team-members could at least give some information about this...

Link to comment
Share on other sites

Far as I know it depends on the Doom3 Sourcecode that isn´t released yet. But id software will most likely do this as they release their newest game. This newest game is called 'Rage'. I was just on their official site and as I clicked at the link for Rage´s teaser site I am redirected to the ElderScrolls!? (that is actually a blank page) So, now I am really confused, so confused that I can´t find the confused-smiley... :wacko:

-> Crisis of Capitalism

-> 9/11 Truth

->

(hard stuff), more
Link to comment
Share on other sites

Without the D3 source code in our hands it's a bit of a moot discussion... and even with the sources released, multi-core support is not just a feature which needs to be added, it's the engine design as a whole which must be suitable for multithreaded execution. Maybe the engine has been designed very well and is future proof enough, maybe the code is specifically optimised for single threaded execution and we need to rewrite large parts of the code, maybe an entire redesign is necessary. It may be hard or it may be very hard, but it will definitely not be easy. There goes a saying is that code will never be suitable for multithreading by accident, the coder needs to keep that in mind right from the start.

 

That said, I had a few sketches in my mind about making the AI processing multi-threaded (something which is within our control), but this has not even made it into the pencil & paper stage.

Link to comment
Share on other sites

That said, I had a few sketches in my mind about making the AI processing multi-threaded (something which is within our control), but this has not even made it into the pencil & paper stage.

 

Interesting. I didn't realize that was possible. Anything else that would be within the teams control?

Link to comment
Share on other sites

Get the entire shadow volume onto the GPU and you'll be fine... (multi-core is secondary to this in my opinion...) But you could just split the screen into sections SFR style and have multiple cores each running an instance of then entire engine...

Please visit TDM's IndieDB site and help promote the mod:

 

http://www.indiedb.com/mods/the-dark-mod

 

(Yeah, shameless promotion... but traffic is traffic folks...)

Link to comment
Share on other sites

You cannot simply "order" operations like that to be done by the GPU. (beside, the renderer-end of shadows is closed source.)

 

and Shadows don't work that way, because they are treated and calculated like actual volumes. And it's those volumetric calculations that take up most performance: not something that split-frame will help at all.

yay seuss crease touss dome in ouss nose tair

Link to comment
Share on other sites

Nvidia has a technical paper about using the Geometry Shader to generate Shadow Volumes: http://http.developer.nvidia.com/GPU...ems3_ch11.html You're saying this couldn't be integrated into Id Tech 4? And maybe for older GPU's you could use R2VB??? http://www.lynxengine.com/old-site/atisdk/R2VB%20Shadow%20volume.pdf ...would either approach be feasible?

Please visit TDM's IndieDB site and help promote the mod:

 

http://www.indiedb.com/mods/the-dark-mod

 

(Yeah, shameless promotion... but traffic is traffic folks...)

Link to comment
Share on other sites

Even if you could get the GPU involved, the difference probably wouldn't be all that great anyway. Doom 3 pre-calculates shadow volumes to non-moving lights, which covers most light sources in a regular map. I doubt that shadow volume calculation is the major CPU bottleneck on a modern PC.

Link to comment
Share on other sites

...if Shadow Volumes are not the primary concern (as was always suggested previously), what is the current biggest CPU consumer of concern, physics, AI?

Please visit TDM's IndieDB site and help promote the mod:

 

http://www.indiedb.com/mods/the-dark-mod

 

(Yeah, shameless promotion... but traffic is traffic folks...)

Link to comment
Share on other sites

Having seen a few of the physics engines available out there and what they can do I certainly hope it is NOT physics that consume a lot of CPU (even though Ishtvan et all have worked wonders with what we do have!).

 

TDM seems to have a sizeable effect on CPU through AI I would say, just from my editing experience. Let's hope the coding gurus around here can split that over several cores in the future :)

Link to comment
Share on other sites

ATI Showed an SDK sample of GPU accelerated path-finding... so that part of the AI equation has been shown to be a parallel workload. (I have no idea how hard it would be to do the same for an Open Source team and on a CPU???). But I've heard that most other AI stuff is highly serial. I guess you could give each guard their own thread when we have 12-thread or higher systems in mainstream? I kinda wish some company would pull a PhysX and create an AI accelerator.

Please visit TDM's IndieDB site and help promote the mod:

 

http://www.indiedb.com/mods/the-dark-mod

 

(Yeah, shameless promotion... but traffic is traffic folks...)

Link to comment
Share on other sites

There's plenty of AI middleware, but it doesn't solve anything as it would be so proprietary that it wouldn't really be usable in TDM. Open source solutions like recast/detour will be fine, but its still a hell of a lot of work for one person to do.

In general GPU acceleration is not something that is quick, easy or generally worth the nightmare it is to try and make widely accessible and as such would be lowest on the list. OpenCL might change that... but its still an incredible amount of work and effort. Just remember that changes like these would have to apply to everyone, no "If he has x vendor use y" type stuff. All in all thinking about GPU acceleration of tasks like this is best completely ignored until such time as its remotely possible and we have interested parties.

 

At the end of the day the real benefit will be in looking for clever ways to change the shader to allow our currently "expensive" shaders and such to become cheaper, in that line maybe we can make some assumptions for shadows but I don't see anyone willing to do anything completely radical. Low hanging fruit is always picked first. Seperating AI out would be quite a large effort but it's something that would help a lot.

 

At the end of the day it all boils down to how many devs you have and how much time they have to make things happen, and at the moment TDM is low on both, so if you're interested and reading this... the source package is on the download page ;)

Link to comment
Share on other sites

hm, too bad that such tasks would eat up THAT much time... however, its always worth to - at least - think over ways to improve performance; maybe we WILL someday end up with little improvements (f.e. threaded ai-calculation, or whatever). so keep your eyes open, guys smile.gif

 

 

doesn't really fit here but... anyway: just for info, are bloom / hdr mostly calculated by GPU or CPU? blink.gif

Link to comment
Share on other sites

Yeah I only brought up the GPU because it's known to be Parallel so if Path-finding can be helped by a GPU it can be helped by Multi-Core... not that I would have the skill to help with either... If you need a wise-acre armchair developer I can send you links to SDK stuff and theoretical approaches all day :)

Please visit TDM's IndieDB site and help promote the mod:

 

http://www.indiedb.com/mods/the-dark-mod

 

(Yeah, shameless promotion... but traffic is traffic folks...)

Link to comment
Share on other sites

If I read JC Denton's thread at Doom3world correctly, HDR is calculated on the GPU but the process is expensive as the output from the "whole engine render" has to be fed back into the shader as a texture??? http://www.doom3world.org/phpbb2/viewtopic.php?f=56&t=23226&st=0&sk=t&sd=a&sid=f69a6a929472fcd016eb9c286cc5070d

Please visit TDM's IndieDB site and help promote the mod:

 

http://www.indiedb.com/mods/the-dark-mod

 

(Yeah, shameless promotion... but traffic is traffic folks...)

Link to comment
Share on other sites

  • nbohr1more changed the title to [Resolved in TDM 2.06] multi core-support

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recent Status Updates

    • Petike the Taffer  »  DeTeEff

      I've updated the articles for your FMs and your author category at the wiki. Your newer nickname (DeTeEff) now comes first, and the one in parentheses is your older nickname (Fieldmedic). Just to avoid confusing people who played your FMs years ago and remember your older nickname. I've added a wiki article for your latest FM, Who Watches the Watcher?, as part of my current updating efforts. Unless I overlooked something, you have five different FMs so far.
      · 0 replies
    • Petike the Taffer

      I've finally managed to log in to The Dark Mod Wiki. I'm back in the saddle and before the holidays start in full, I'll be adding a few new FM articles and doing other updates. Written in Stone is already done.
      · 4 replies
    • nbohr1more

      TDM 15th Anniversary Contest is now active! Please declare your participation: https://forums.thedarkmod.com/index.php?/topic/22413-the-dark-mod-15th-anniversary-contest-entry-thread/
       
      · 0 replies
    • JackFarmer

      @TheUnbeholden
      You cannot receive PMs. Could you please be so kind and check your mailbox if it is full (or maybe you switched off the function)?
      · 1 reply
    • OrbWeaver

      I like the new frob highlight but it would nice if it was less "flickery" while moving over objects (especially barred metal doors).
      · 4 replies
×
×
  • Create New...