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    shared memory

    Yes, I shudder at the thought also, but i noticed something today when playing with the 'graphicsconfig' in autocad 2011...

    3D Device
    ---------
    Name : NVIDIA GeForce GTX 460
    Manufacturer : NVIDIA
    Chip set : GeForce GTX 460
    Memory : 4065 MB
    Driver : 8.17.0012.7051
    now, obviously they dont make a GTX 460 with 4gb of ram. i have the 1GB version. is there a way that autocad is using shared memory for their driver (since i dont have a special quadro driver)?

    in the same regard, could this be happening in revit also?
    since we only really have 2 3D options in revit
    "use hardware acceleration"
    "use anti-aliasing for 3D views"

    i only bring this up as i was testing the newer beta geforce drivers. I noticed the using gpu-z to show the gpu load, it never really got about 5% regardless of if i had 3D enabled in autocad or revit. I also noticed that whether i had 3d enabled or disabled in autocad or revit 2011, my cpu usage would max out at about 15%.

    we share our office space with an civil firm, they have civil 3D. gpu usage (autocad 3d enabled) maxes out @ 30%, and stays in the 0-5% range with it disabled (assuming 5% is just windows aero, even though we both have them configured as windows basic to reduce on system overhead)

    specs:
    i7 870
    8gb ddr3 1600
    geforce gtx 460, currently 270.51 beta driver (previously 267.91, 267.24 beta, 266.58, and 260.99)
    win7 x64

    comments, personal experiences?
    Last edited by btrusty; April 14, 2011, 01:58 PM.

    #2
    I don't know where AutoCAD pulls that figure from... but it doesn't really matter... it's not really "correct".

    I'd be interested in GPU-Z - I think I tried it once before but it was incompatible with my video card or something. Regarding video performance in Revit, you can read up on my experience here and here.

    You're typically seeing no more than about 15% of the CPU side because you've got 8 virtual cores (quad core x 2 because of hyper-threading)... so when Revit is using 1 core full on, it's 100% / 8. If you do a rendering, you see that jump to about 100% since rendering will use all cores.

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      #3
      @iru69

      i understand that, i just thought it was ironic that regardless of having 3D selected in autocad / revit it had no difference in CPU usage, as in it didnt matter if i had 3D selected or not, it wasnt using the gpu to "speed anything up". except that in this latest beta driver i was getting all kinds of artifacts for both autocad and revit. it also didnt seem to have any performance difference for either autocad or revit regardless of the 3D selected/de-selected...

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        #4
        btrusty,

        I will say this. I added some GPU benchmark stuff to the RFOBenchmark specifically to try to measure the value of a $500 graphics card over a $50 card. And yet the results suggest no difference whatsoever. And yet, the test proves in no uncertain terms that having hardware acceleration enabled is hugely important, at least if shadows and/or ambient occlusion is on. And that jives my butt dyno experience. Which leaves me to believe this. Hardware Acceleration only uses a small portion of the capability of the graphics hardware, but that hardware is a thousand times better at the task than the general purpose CPU, so you can see a huge performance boost while the graphics card is basically not even breaking a sweat. And when HA is off, you don't see a spike in CPU use because the capabilities for doing the work are limited, and get lost in the trace of all the other stuff going on. But all that is a theory, based on anecdotal info. I would love to be able to actually observe GPU use and maybe validate that whole theory.

        EDIT: I just installed GPU-Z 0.4.6 and ran a few tests in RAC 2012. Before Revit launched, GPU-Z claimed no GPU load, and only 90MB of VRAM used. I opened Revit and the Simple Sample file. In a Realistic view, VRAM use spiked to 157MB, but switching to Consistent colors made it go up to 161 MB, and my understand was that only realistic view textures where stored in VRAM. Beyond that, when just looking at the view, GPU load sits at 0-1%. But when I spin the view around with Shadows and Ambient SHadows off, I get GPU Load spiked to around 15%. Turn shadows and ambient occlusion on and the spike goes to 25%. All of which leads me to believe that the GPU is doing a lot, but Revit is not taxing it at all. But for me at least there is very measurable activity, at least as far as GPU-Z is concerned.

        Gordon
        Pragmatic Praxis

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          #5
          Thanks Gordon,

          FYI gpu-z is up to 0.5.3. i doubt it will show you much difference in hardware utilization, but you never know.

          that that point, i wonder if having a newer sandy bridge with integrated 3000 graphics would be enough to run revit (saving even further on the graphics component)

          i was testing the beta drivers and was having more and more "texture tearing" and screen "artifacting" with HA on. the worst is when the revit view goes completely black. the other major issue is when revit gets the "waiting" as if it is working or it has crashed and windows doesnt know yet. this has been worst on some of the latest beta drivers when saving to central (network). it would not respond for 10-20 minutes sometimes.

          i left it one day and went to lunch. when i can back, i made 2 quick changes, saved again and 10-20minutes!? i disabled HA, closed and opened revit again. did the same thing and it saves in 10 seconds (10 seconds with HA off verses 10 minutes with HA on!?!?!)

          I will probably go back to 260.99 or 266.58, though i need no real performance difference with typical revit usage (design, producing CD's without shadows) with HA off. Shadows definitely feels faster with HA on. Havent done that much with Realistic or Consistent Colors in daily work.

          I just wonder if there is a way to take away the lag when you have 3+ dwg underlays that are greater than 5mb each... yea, yea, unload them...

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