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AFX CC - RAM management

Aug 30, 2013 4:08 AM

Hello,

 

with after effects CC it still seems like the multi CPU rendering is not always working properly..

When i render a sequence on a dual 6 core Xeon (24 threads) with 48 GB of RAM, it starts very fast and the CPU usage is between 95 and 100%. The amount of used RAM grows fast until it is completely filled up and then it gets realy slow. The CPU goes from 15% to 100 and back to 0.. stays on 0... from 0 to 15 to 0..and some times to 100%. Like its always cleaning only enough ram to render the next bunch of frames, which makes it very slow.

I am not a programmer but isnt it possible to clean up RAM constantly like every multi CPU 3D rendering program?

Or is the problem somewhere else?

 

Best,

David

 
Replies
  • Currently Being Moderated
    Aug 30, 2013 6:49 AM   in reply to Shader3d

    What settings do you have for your multiprocessing, CPU cores, and RAM allocations?

     

    Check out the info here.  It's written for CS5, but still applies to CC.  If you're rendering with all 24 threads, you probably don't have enough RAM.  Check out the "Don't starve your software of RAM" article.  For HD video, you'll want at least 2GB (preferably 3GB) for each thread.

     
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  • Currently Being Moderated
    Aug 30, 2013 6:53 AM   in reply to Shader3d

    isnt it possible to clean up RAM constantly like every multi CPU 3D rendering program?

     

    Per-pixel shader evaluations simply work completely differently. 3D programs don't explicitly "clean" anything in most cases, that stuff is inherent in how to build and optimize the underlying acceleration and evaluation structures. Still, even a 3D program will get bogged down when needing to store lots of pixel data (textures) and gobble up all your RAM. That's just what this is. And since a lot of pixel math requires lots of integer operations for building lists, color tables and calculating coordinates, there is only limited potential for optimizations without redundantly duplicating the data - just like with MP rendering. Add to that general limitations like operating systems not allowing multiple processes to the same file and the resulting wait cycles and al lof that and you will see how AE's current MP model never can go beyond certain limits even on the most beefy machine... That is to say what you are seeing - within those bounds - is normal, though of course ther specifics may vary from project to project. This has been discussed a million times, so do a little digging on the forum.

     

    Mylenium

     
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    Sep 12, 2013 6:32 AM   in reply to Shader3d

    I had the same issues on my workstation. After a lot of fiddling (Win7 64):

    I've always used quicktime as the intermediate format between editing and compositing: export QT-'same as source' from Avid, import in AE, compositing, export as QT'same as source' back to the Avid timeline. But my new system has dual six core CPU's and AE did not perform anymore. Since QT is 32-bit only, Adobe has made 'Adobe QT32 Server.exe' component to make Quicktime behave on 64-bit systems. But the more cores/threads, the slower it gets. It's a bottleneck, so to speak. I switched from quicktime to tiff-sequences as intermediate format (not as handy, of course). Now AE is remarkably fast. It flies and renders as I expect it to.

     

    Another bottleneck is hyperthreading. This feature lets the OS believe there are more cores than physically available. But when using AE (or Lightwave or other CPU-intensive software) you're using 100% of the CPU cycles anyway. Hyperthreading makes AE use all of the virtual cores, rendering more images at once, but slower, since it's the same processor power spread thinner.

    So my solution was twofold: abandoning Quicktime and disableing hyperthreading.

     

    Since tiff-sequences are not as handy I found a great little tool to watch image sequences as one file: djv_view. Google it, it's free. I would like to see image-sequence-handling appear in Bridge, though.

     

    Regards,

    Wim

     
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  • Currently Being Moderated
    Sep 12, 2013 9:45 AM   in reply to Shader3d

    We just upgraded some of our machines and have 4 of the new ones that are 16 cores each with 64GB ram. In all of my testing i determined the best thing to do was turn off Multithreading also like others said. 32 copies of after effects running at same time just doesnt seem efficient.

     

    So i run 16 threads with 3GB ram set for each and that is the fastest rendering I was able to acheive. The 3GB settings for me was about 25% faster than the 2GB setting

     
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