4 Replies Latest reply on Feb 10, 2011 8:52 PM by Todd_Kopriva

    memory and multiprocessing issue

    lewisfilms Level 1

      I have a machine with an i7 quad-core processor and 12gigs of RAM.  When I turn on mulitprocessing, my performance actually seems to diminish. Why would that happen?  Here is a link to a detailed snapshot of my settings:

       

      http://yfrog.com/f/h45as5j/

       

      Thanks for any help!

      -Steve

       

      PS: the comp I was working on during the time was 1920x1080 at 23.976fps and had 50 layers text and a few layers of Glow  (working in 32bpc)

        • 1. Re: memory and multiprocessing issue
          Todd_Kopriva Level 8

          Using the Render Multiple Frames Simultaneously multiprocessing feature does not speed up the rendering of all compositions. The rendering of some compositions is memory-intensive, such as when you are working with very large background plates that are several thousands of pixels tall and wide. The rendering of some compositions is bandwidth-intensive (I/O-intensive), such as when you are working with many source files, especially if they are not served by a fast, local, dedicated disk drive. The Render Multiple Frames Simultaneously multiprocessing feature works best at improving performance when the resource that is most exercised by the composition is CPU processing power, such as when applying a processor-intensive effect like a glow or blur.

           

          Tell us about your disk drive setup.

          1 person found this helpful
          • 2. Re: memory and multiprocessing issue
            lewisfilms Level 1

            Thanks Todd,

            Could you tell me if I had a sensible configuration of the settings in that snapshot?  I only started working with AE about 2 weeks ago, so thanks for helping me out.  Right now, I am working with a single drive.  (i know, I should have seperate drives for media, I will do that ASAP)  The comp has nested comps with psuedo 3d text (50 layers of text)  with about 5 layers contaning the Glow effect.  It just seems that turning on the Multiprocessing would help simply because AE can address more RAM that way, right?

             

            -Steve

            • 3. Re: memory and multiprocessing issue
              Todd_Kopriva Level 8

              > Could you tell me if I had a sensible configuration of the settings in that snapshot?

               

               

              In general, four processor cores really isn't enough to use Render Multiple Frames Simultaneously effectively. There are some exceptions, but consider this:

              You need to leave at least one processor for other applications, which gets you down to three. Then you need to have a foreground instance of the application running to manage the whole process, bringing you down to two rendering processes. That's twice the possible rendering throughput, but at triple the overhead... which often isn't worth it. If you were processing huge plates with complex glows and blurs (which are CPU intensive), then it might be worth it. But if your operations are I/O-bound, then there's probably not going to be much gain.

              > It just seems that turning on the Multiprocessing would help simply because AE can address more RAM that way, right?

               

              It's not that simple.

               

              Different settings make more sense in different circumstances. That's why these are preferences that you can turn on and off and tweak, If something were always the right answer, we'd turn it on and not give you any buttons to press.

               

              The right mindset isn't "This button should always make things faster!" Rather, the right mindset is to learn in which case different options help, and in which cases they hinder. Run a simple test on a portion of your composition with a few different setitngs, then use the settings that work best for that scenario. Pretty soon, you'll learn the particulars of your own setup and you'll know how to set things.

               

              > Right now, I am working with a single drive.  (i know, I should have seperate drives for media, I will do that ASAP)

               

              That is very, very often the cause of poor performance. If you fire up two or three copies of the After Effects application (which is what's happening when you use Render Mutliple Frames Simultaneously multiprocessing), then you need to be able to feed all of them with source data. If you're running the OS and application from the same drive from which you're reading source data, and you're also trying to write output to the same drive, the thrashing that the hard disk has to do to keep up is wasteful.

               

              The collected wisdom of the After Effects team is here and in the pages that it points to:

              http://forums.adobe.com/thread/543440

              Feel free to ask questions, but please do read these resources.

               

              BTW, memory handling is _much_ better in After Effects CS5. That's most of what we improved in that version. If you really care about performance and memory handling, I recommend using After Effects CS5.

              • 4. Re: memory and multiprocessing issue
                Todd_Kopriva Level 8

                > I only started working with AE about 2 weeks ago...

                 

                 

                I recommend starting here:

                http://blogs.adobe.com/toddkopriva/2010/01/getting-started-with-after-eff.html