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AE CS4 Multiprocessor Settings for iMac Quad-Core i7?

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Nick LievendagAE CS4 Multiprocessor Settings for iMac Quad-Core i7?
by on Jan 20, 2010 at 12:29:01 am


My iMac with Quad-Core i7 arrived a few days ago. Nice piece of hardware (and I'm lucky min has no issues!), but I'm trying to figure out the best config for AE CS4 multiprocessor rendering.

I've allready read this thread:

My projects are on a 1TB WD MyBook Studio in RAID 0 over FW800. My Disk cache is 10GB on the local HD. I also render to the local HD.

I now about the virtual cores on the i7 so AE sees 8 cores. My system has 8gb RAM installed, so 2GB over 4 Cores was my guessed setting, although it only lets me use 3 when I select 2GB since I have to leave 0,25GB for other apps. But now it renders significantly slower than without the multiprocessing on. The render doesnt seem fluid on screen. It hangs every x frames and than continues.

So I put in to do 2GB (2,09 actually) over 2 cores and that actually speeds up the rendering quite much and seems smooth.

So I have the feeling that this system doesn't let me go all the way with the 4 cores.

Render Times:
- no MP: 17min
- MP 2gb over 3 cores: 24min
- MP 2gb over 2 cores: 9min

What could be the bottleneck here? Is it the firewire 800? Since that's all I have since the iMac SADLY doesn't speak eSata :-P

Thanks in advance!


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Todd KoprivaRe: AE CS4 Multiprocessor Settings for iMac Quad-Core i7?
by on Jan 20, 2010 at 1:06:09 am

Start by reading this.

Todd Kopriva, Adobe Systems Incorporated
putting the 'T' back in 'RTFM' : After Effects Help on the Web
If a page of After Effects Help answers your question, please consider rating it. If you have a tip, technique, or link to share---or if there is something that you'd like to see added or improved---please leave a comment.

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Kevin CampRe: AE CS4 Multiprocessor Settings for iMac Quad-Core i7?
by on Jan 20, 2010 at 4:23:03 pm

another thing you can do as you try your own benchmarks with various settings, is to run the activity monitor (applications>utilities>activity monitor).

that app will let you see the various processes that are running on you mac. when you render with multiprocessing on, you'll see some processes called aeselflink. these are the render engines that ae uses when multiprocessing is enabled (one for each core that is set in the multiprocessing prefs).

the values you are interested in are the cpu values. when you see values that are around 100, that means that the process is using about all the resources of a single cpu. you can see values higher than 100 if extra cores are available to help rendering -- so you have 4 cores, but tell ae to use 2... there are 2 available to help rendering when ae is rendering something that is multi-threaded. note that not all effects are multi-threaded, but many are.

if you see values that are much lower than 100, then you are having a data bottleneck somewhere. usually, it's with the ram. with faster and greater numbers of cpus, computers have a greater ability to go through data quickly. by having more ram available, you can help assure that the cpus are running at there full potential and not waiting around for data to process (aka, starving). in a case like that, decreasing the number of cpus increases the amount of ram available and can increase performance.

and, as todd's blog points out, your system has other processes running in the background that need ram to keep things running smooth. so if you tell ae to use all your resources, that can affect performance negatively too.

as far as the drives causing a bottleneck, with 2-4 cores, i don't think that will be a problem often. but with fairly effect light comps with high data rate footage files, you could see a bottleneck. it's easy to demonstrate this, just add 10 hd clips to a comp, all overlapping and set their opacities to 10%, then render (or ram preview). if you look in the activity monitor, you'll probably see that the cpu usage for the aeselflinks is fairly low. this is due to the amount of data that has to travel from the drives, to the ram, then to the cpus... and the cpus are not having to do much processing so they are spitting out frames faster than they can get the data from the drives.

that scenario is not a very common one, so i don't think you'll see that too often. but, perhaps if you did a lot of color correction for uncompressed hd footage, you may be able to speed the process up by having a faster drive option... the imac *may* have an extra sata2 drive bay inside, by getting a fast internal sata2 drive, you *may* be able to improve performance (in a case like this).

Kevin Camp
Senior Designer

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