Results 1 to 12 of 12

Thread: Bullet Dynamics not using all CPU cores.

  1. #1
    Registered User
    Join Date
    Nov 2007
    Location
    Singapore
    Posts
    77

    Bullet Dynamics not using all CPU cores.

    Appalling to see only one core was used for dynamics calculation. Anyway to tweak for better CPU utilization ?

    Click image for larger version. 

Name:	20170901_093546.jpg 
Views:	100 
Size:	310.4 KB 
ID:	137804

  2. #2
    _
    Join Date
    Mar 2003
    Location
    moravia
    Posts
    1,017
    The way they explained it to me was that if Bullet was made multi threaded, it would stop being deterministic, or something like that. So, every time you ran the simulation, the result would be slightly different. The only way to make the simulation be exactly the same every time you rendered or scrubbed the timeline was to make it single threaded.

  3. #3
    Registered User
    Join Date
    Nov 2007
    Location
    Singapore
    Posts
    77
    I find that reasoning rather lame.

    My CPU has 6-cores, so technically it is only using half a core for calculation, wasting the rest of the cores.

  4. #4
    Registered User squarewulf's Avatar
    Join Date
    Aug 2014
    Location
    South Bend, Indiana
    Posts
    399
    Quote Originally Posted by blackmondy View Post
    I find that reasoning rather lame.
    A bit. They should give us an option, sometimes I couldn't care less if the sim was slightly different every time. Other times, like working with a group on a big project, I definitely would need the sim to be consistent. Making an option to use all cores and risk variation would be nice.

  5. #5
    Axes grinder- Dongle #99
    Join Date
    Jul 2003
    Location
    Seattle
    Posts
    14,732
    Do other/all Bullet implementations require single-thread operation?

    If not, then that reason was b.s.

    You know who can whip up plausible rationalizations at the snap of a finger? Clever people. Like programmers.
    They only call it 'class warfare' when we fight back.
    Praise to Buddha! #resist
    Chard's Credo-"Documentation is PART of the Interface"
    Film the cops. Always FILM THE COPS. Use this app.

  6. #6
    Scene Destroyer DrStrik9's Avatar
    Join Date
    May 2007
    Location
    Portland, Oregon
    Posts
    1,684
    Quote Originally Posted by jeric_synergy View Post
    Do other/all Bullet implementations require single-thread operation?
    I'm no developer, but I can tell you that Blender's bullet calculations are MANY times faster than LW's. This leads me to suspect that Blender's calculations are multi-threaded. But that's just a guess.

  7. #7
    Super Member Snosrap's Avatar
    Join Date
    Aug 2004
    Location
    Ohio, USA
    Posts
    4,923
    Bullet is not (yet) multithreaded or GPU accelerated. It's slow due to LW's old underlying structure. Bullet was amazingly fast in LW Core.

  8. #8
    Axes grinder- Dongle #99
    Join Date
    Jul 2003
    Location
    Seattle
    Posts
    14,732
    Quote Originally Posted by DrStrik9 View Post
    I'm no developer, but I can tell you that Blender's bullet calculations are MANY times faster than LW's. This leads me to suspect that Blender's calculations are multi-threaded. But that's just a guess.
    You can just open.... dang... Task Manager, use the CPU tab, and watch the various cores to see if they get utilized.
    They only call it 'class warfare' when we fight back.
    Praise to Buddha! #resist
    Chard's Credo-"Documentation is PART of the Interface"
    Film the cops. Always FILM THE COPS. Use this app.

  9. #9
    Electron wrangler jwiede's Avatar
    Join Date
    Aug 2007
    Location
    San Jose, CA
    Posts
    6,509
    Quote Originally Posted by Snosrap View Post
    Bullet is not (yet) multithreaded or GPU accelerated. It's slow due to LW's old underlying structure. Bullet was amazingly fast in LW Core.
    Well, as of Bullet 2.80 there's a completely 100% GPU-computed rigid body pipeline preview available (Takiro Harada's work) for both AMD and Nvidia (and this is distinct from the 3.x stuff). See this GitHub issue for status on a preview multithreaded Bullet implementation.
    John W.
    LW2015.3UB/2019.1.4 on MacPro(12C/24T/10.13.6),32GB RAM, NV 980ti

  10. #10
    Houdini has a "use Parallel constraint solver" option which enables Multithreaded solving, sometimes I use it, sometimes not. It can cause the results to be a little wonky as the velocity of the collisions is calculated differently. If I where happy with a solve using single thread calc, and then just wanted to speed up the calculations. I would get a different result after enabling the parallel constraint option.

    Click image for larger version. 

Name:	Houdini_Bullet.jpg 
Views:	77 
Size:	1.66 MB 
ID:	137816.

  11. #11
    Super Member Snosrap's Avatar
    Join Date
    Aug 2004
    Location
    Ohio, USA
    Posts
    4,923
    Quote Originally Posted by jwiede View Post
    Well, as of Bullet 2.80 there's a completely 100% GPU-computed rigid body pipeline preview available (Takiro Harada's work) for both AMD and Nvidia (and this is distinct from the 3.x stuff). See this GitHub issue for status on a preview multithreaded Bullet implementation.
    Sweet. Good to know.

  12. #12
    Vacant, pretty vacant pinkmouse's Avatar
    Join Date
    Aug 2003
    Location
    South Yorkshire
    Posts
    1,702
    Quote Originally Posted by Snosrap View Post
    Sweet. Good to know.
    Indeed, but I very much doubt we'll see that in Next. As usual, the Bullet we get will likely be about three years out of date.
    Al
    "I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while." Charles Fort

    My Website
    My Lightwave Tutorials

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •